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1  "23 
SOUTHERN   BRANCH 

UNIVERSITY  of  CALIFORNIA 
LIBRARY 

LOS   ANGELES. CALI!F< 


A   SYSTEM 
OF    PSYCHOLOGY 


A    SYSTEM 
OF    PSYCHOLOGY 


BY 
KNIGHT   DUNLAP 

ASSOCIATE     PROFESSOR     OK     PSYCHOLOGY     IN     THE 
JOHNS     HOPKINS     UNIVERSITY 


NEW   YORK 

CHARLES   SCRIBNER'S   SONS 

1912 

3^7^ 


Copyright,  1912,  by 
CHARLES  SCRIBNER'S  SONS 


. 


if 


TO 

ELMER  ELLSWORTH  BROWN 

IN    ACKNOWLEDGMENT    OF   WHAT    I    OWE   TO    HIS 
TEACHING    AND    FRIENDSHIP 


PREFACE 

I  should  not  be  willing  to  add  to  the  large  num- 
ber of  psychology  texts  already  in  existence  did  I 
not  believe  that  this  book,  in  spite  of  its  faults  of 
rf\  omission  and  commission,  possesses  certain  good 
fj  points  not  found  in  the  other  English  texts  of  re- 
cent date. 

My  greatest  effort  has  been  to  present  as  consist- 
ent and  systematic  a  sketch  as  possible  of  the  general 
—  field  of  normal  human  psychology,  elaborating  the 
details  only  when  they  are  essential  to  the  general 
survey.  In  a  field  which  is  in  great  and  increasing 
danger  of  becoming  unsystematized  to  the  point  of 
chaos,  even  to  the  trained  specialist,  this  method 
of  introduction  is  absolutely  essential. 

I  have  tried  to  show  that  the  data  of  psychology 
cannot  at  present  be  definitely  described  except  in 
terms  of  theories  which  are  more  or  less  "philosoph- 
ical," and  that  the  attempt  to  divorce  the  data  from 
the  theories  would  result  in  the  uncritical  acceptance 
of  fragments  of  theories.  It  is  important  that  the 
student  should  grasp  this  truth  in  the  beginning, 


Vlll  PREFACE 

and  not  be  taught  a  pseudo-final  system  of  facts 
which  later  must  crumble  cataclysmically  when  he 
takes  a  new  point  of  view. 

I  have  not  attempted  to  write  a  book  so  simple 
that  the  student  might  read  and  understand  it 
without  effort:  rather,  I  have  endeavored  to  write 
that  which  should  demand  and  reward  hard  study. 
The  book  is  not  designed  to  be  made  the  sole  basis 
of  a  course  in  elementary  psychology.  It  ought  to 
be  accompanied  by  lectures  prepared  by  a  com- 
petent teacher,  having  special  reference  to  the 
difficulties  and  lacunae  of  the  text,  and  to  its  dif- 
ferences from  the  psychological  theories  held  by 
the  teacher.  Certainly,  the  book  cannot  be  used  as 
a  text  from  which  both  students  and  teacher  may 
draw  their  information.  As  a  main  or  supplement- 
ary text  for  semiadvanced  students,  it  should  find 
its  greatest  usefulness. 

The  only  originality  I  can  claim  is  in  the  way  in 
which  I  have  worked  up  materials  borrowed  from 
many  places.  I  have  not  given  credit  for  my  bor- 
rowings, because  in  many  cases  the  sources  are  too 
obvious  to  be  mentioned,  and  in  other  cases  what 
has  been  borrowed  has  been  so  distorted  in  the  proc- 
ess that  the  individual  to  whom  I  am  indebted 
might  resent  the  ascription   if  credit  were  given. 


PREFACE  IX 

The  chief  influences  which  have  shaped  my  psy- 
chological constructions  have  come  from  the  writ- 
ings of  James  and  from  my  contact,  as  a  pupil,  first 
with  Howison,  later  with  Stratton,  and  finally  with 
Miinsterberg. 


CONTENTS 

CHAPTER  PAGE 

I.     Introduction: 

1.  The  Meaning  of  Psychology      ....  1 

2.  Terminology        5 

3.  Extrinsic  Helps 8 

II.     Preliminary  Analysis  of  Content: 

1.  Complexity  of  Content  and  Complexity 

of  Experience 12 

2.  General    Classification    of    Elements    of 

Content 13 

3.  Terminology 16 

III.    Sensation  in  General: 

1.  Sensation,  Physical  Stimulus,  and  Physi- 

ological Process 18 

2.  Matter  and  Psycho-Physical  Causation   .  25 

3.  The  Lag  of  Sensation 27 

4.  Secondary  Sensations 31 

5.  The  Characters  of  Sensation      ....  32 


IV.    Sensation-Quality: 

1.  General  Classification       38 

2.  Sensation  and  Brain  Process      ....  43 

3.  Sensations  of  Taste 44 

4.  Sensations  of  Smell 49 

5.  Visual  Sensations 54 

6.  The  Schematic  Representation  of  Visual 

Qualities 56 

7.  Achromopsia  and  Parachromopsia      .     .  67 

8.  Color  Adaptation  and  Contrast      ...  74 

9.  Auditory  Sensations 80 

10.  Cutaneous  and  Subcutaneous  Sensations  84 

11.  Kinaesthetic  and  Ccensesthetic  Sensations  95 

xi 


XI 1  CONTENTS 

CHAPTER  PAGE 

V.    Thresholds  of  Consciousness       .... 

1.  Stimulus-Thresholds 101 

2.  Stimulus  Difference  Thresholds      .     .     .  105 

3.  Other  Thresholds 106 

4.  The  Constant  Error 106 

VI.    Sensation-Intensity: 

1.  Intensity  of  Sensation  and  Intensity  of 

Stimulus 109 

2.  Weber's  Law Ill 

3.  The  Comparison  of  Intensity-Differences  114 

4.  The  Relativity  of  Sensation       ....  116 

5.  Beats 118 

VII.     Protensity  and  Extensity  of  Sensation: 

1.  The  Duration-Quality 120 

2.  Extensity 122 

3.  Overtones  and  the  Musical  Scale  .     .     .  125 

4.  Timbre 132 

5.  Extensity  and  Intensity 134 

VIII.     Local  Significance: 

1.  Localization  and  Local  Sign      ....  137 

2.  The  Discrimination  of  Local-Sign  Differ- 

ences         139 

3.  Local  Sign  in  Auditory  Sensation.      .     .  143 

4.  Olfactory  Local  Sign 145 

IX.    Relational  Elements  in  the  Content  of 
Consciousness: 

1.  General 146 

2.  Platonic  Ideas  and  Matter 149 

3.  Intellect 150 

\                  4.  The  Reality  of  Relational  Content     .     .  151 

-J     X.     Images  as  Elements  of  Content: 

1.  Imagination  and  "Image  Types".       .     .  153 

2.  The  Function  of  Imagination    .     .     .     .  160 


CONTENTS  Xlll 

CHAPTER  PAGE 

XI.    Retention,  Memory,  and  Recall: 

1.  Retention 100 

2.  Memory 174 

3.  Recall 177 

fXII.     Association: 

1.  The  Principles  of  Association    ....  180 

2.  Voluntary  Recall 102 

3.  The    Probable    Physiological    Basis    of 

Association 104 

XIII.  Perception: 

1.  The  General  Nature  of  the  Content  in 

Perception        106 

2.  Perception,  Illusion,  and  Hallucination    .  201 

3.  The  Determination  of  Perceptual  Truth 

and  Falsity 205 

4.  The  Causes  of  Illusion 208 

5.  Space  Perception 212 

6.  The  Perception  of  Things 227 

7.  The  Perception  of  Time 220 

XIV.  Affective  Content,  or  Feeling: 

1.  Affection  and  Cognition 242 

2.  Pleasure  and  Pain 244 

3.  Conation  and  Interest 250 

4.  Emotion 255 

5.  The  Coenaasthetic  Factor  in  Emotion  .     .  250 

6.  The  Cognitive  Factor  in  Emotion        .     .  261 

7.  The  Classification  of  the  Emotions     .     .  263 

XV.    Action  and  Will: 

1.  Action  in  General 265 

2.  Volition .270 

3.  Volition  as  Activity 273 

4.  Automatic  Action 274 

5.  Instinctive  Action  and  Learning     .     .     .  277 

6.  Habit 281 


XIV  CONTENTS 

CHAPTER  PAGE 

XVI.     The  Self,  or  Empirical  Ego 285 

J      XVII.    The  Degrees  op  Consciousness: 

1.  Consciousness,  Attention,  and  Vividness  .  292 

2.  Vividness  and  Intensity 295 

3.  Factors  Determining  Vividness       .     .     .  298 

4.  Attention  and  Interest 301 

5.  Vividness  and  Practical  Advantage     .     .  302 

6.  Judgment 303 

7.  The  Scope  of  Attention 304 

XVIII.    The  Time  Relations  of  Consciousness: 

1.  Presentation  and  Image 306 

2.  Rhythm 309 

3.  Duration  of  Attention   to  Continuously 

Presented  Sensation 313 

4.  The  Fluctuations  of  Minimal  Sensations  316 

5.  The  Selective  Fluctuation  of  Vividness    .  318 

6.  The  Conditions  of  Constant  Attention    .  323 


\ 


XIX.    The  Subconscious: 

1.  The  Lower  Limit  of  Vividness       .     .     .  325 

2.  What  the  Subconscious  is  Not  ....  326 

3.  The  Two  Sorts  of  Marginal  Consciousness  328 

4.  Multiple  Personality 331 

XX.    The  Ego 336 

XXL    The  Occult: 

1.  The  Study  of  the  Occult 342 

2.  Telepathy       343 

3.  Mysticism       348 

4.  Spiritualism  and  Mediumship    ....  350 

References 355 

Index 363 


A   SYSTEM 
OF    PSYCHOLOGY 


A  SYSTEM 
OF  PSYCHOLOGY 

CHAPTER  I 

INTRODUCTION 
i.  The  Meaning  of  Psychology 

It  is  much  easier  to  tell  the  beginner  what  psy- 
chology is  not  than  it  is  to  tell  him  what  psychology 
is.  Just  as  it  would  be  impossible  to  give  an  in- 
telligible definition  of  mathematics  to  a  person  un- 
familiar with  the  elementary  principles  of  number- 
relations,  so  it  is  impossible  to  make  clear  to  the 
average  student  the  nature  of  psychology  when  he 
is  just  beginning  to  study  it.  In  order  that  one 
may  have  a  definite  idea  of  what  psychology  is,  he 
must  know  some  psychology;  and  a  person  who 
has  not  studied  the  subject  under  competent  guid- 
ance is  not  apt  to  know  any  psychology  in  the  strict 
sense.  It  is  true,  on  the  one  hand,  that  there  is  a 
great  deal  of  information  which  is  popularly  called 
psychological;  and,  on  the  other  hand,  that  every 


2  A   SYSTEM   OF   PSYCHOLOGY 

person  knows  much  that  is  really  psychology,  al- 
though the  persons  in  question  do  not  realize  that 
it  is  such.  These  two  species  of  misunderstanding 
contribute  to  the  difficulty  of  the  task  when  one 
commences  to  study  the  subject  scientifically.  It 
is  clear,  therefore,  that  what  we  say  now  in  a  general 
way  concerning  psychology  should  be  brief,  and 
that  the  meaning  thereof  will  probably  be  clear  to 
the  student  only  as  he  reverts  to  it  after  completing 
the  volume. 

We  may  commence  advantageously  by  warning 
the  student  against  some  of  the  more  common 
misconceptions  of  psychology.  In  the  first  place, 
while  on  the  one  hand  psychology  is  not  the  "  study 
of  the  soul,"  on  the  other  hand  it  is  not  "soulless" 
in  the  sense  of  doing  away  with  a  soul.  It  is  a  com- 
monplace that  yjrvxoXoyia  is  not  to  be  taken  in  its 
literal  significance  as  the  name  of  our  field  of  labor, 
and  that  a  considerable  portion  of  the  psychologi- 
cal discussion  gets  along  without  any  mention 
of  any  sort  of  "soul."  But  in  a  comprehensive 
analysis  it  is  not  possible  to  avoid  reference  to 
something  which  may  properly  be  called  a  "soul," 
although  it  is  by  no  means  the  "psyche"  of  the 
Greeks  and  of  the  current  popular  conception,  and 
although  it  is  impossible  really  to  study  it. 


INTRODUCTION  -5 

In  the  second  place,  psychology  deals  very  little 
with  the  so-called  "occult";  with  telepathy,  clair- 
voyance, and  the  other  charlatanisms  which  are 
often  so  successfully  employed  in  separating  the 
fool  from  his  money.  Yet  if  we  do  not  affirm, 
neither  do  we  deny,  that  there  may  be,  at  the  core 
of  some  of  these  concretions  of  humbuggery,  cer- 
tain elements  of  psychological  interest  and  impor- 
tance. The  investigation  of  such  matters  belongs, 
however,  not  properly  to  psychology,  but  to  "psy- 
chic research." * 

In  the  third  place,  the  term  "psychological"  in 
current  popular  usage  designates  a  certain  delicacy 
or  niceness  of  discrimination  or  adjustment.  Thus 
the  "psychological  moment"  implies  an  instant  of 
time  so  appropriate  for  a  certain  act  that  a  moment 
before  would  be  too  early,  and  a  moment  after  too 
late.  Any  very  precise  analysis  or  description, 
of  the  characteristics  and  activities  of  human  be- 
ings; or  even  a  simulation  of  precision,  is  called 
"psychological";  and  hence  we  find  mention  of 
"psychological"  novels,  and  so  forth.  Now  while 
psychology  modestly  acknowledges  the  pretension  to 

'The  terms  "psychic"  and  "psychical"  must  be  distin- 
guished carefully  from  "psychological."  It  is  to  be  regretted 
that  either  of  the  first  two  terms  is  ever  applied  to  the  data 
which  we  study  in  the  name  of  psychology. 


4  A   SYSTEM  OF  PSYCHOLOGY 

exactness  of  analysis,  she  must  deny  any  exclusive 
claim  thereto,  and  cannot  even  pose  as  the  only 
science  which  analyzes  human  activity  and  ex- 
perience. In  this  popular  sense  of  the  term,  physi- 
ology, logic,  and  ethics  are,  if  anything,  more  "  psy- 
chological" than  is  psychology. 

Finally,  psychology  is  not  the  study  of  the  func- 
tions of  the  nervous  system.  In  fact,  all  the  essen- 
tial points  of  psychology  can  be  expounded,  as  they 
have  been  developed,  without  reference  to  the  ner- 
vous system,  or  by  reference  to  a  conception  thereof 
which  is  ridiculously  inaccurate.  Nevertheless,  it 
is  true  that  psychological  principles  and  facts  are 
more  easily  described  and  investigated  when  re- 
ferred to  the  structure  and  probable  activity  of  the 
brain  and  nerves,  as  understood  by  the  person  to 
whom  described  or  by  whom  investigated,  and  we 
believe  that  the  more  closely  the  physiological  con- 
ceptions approach  agreement  with  the  actual  facts  of 
structure  and  function,  the  more  facile  the  progress 
of  psychology. 

As  for  a  positive  definition  we  may  give  the  fol- 
lowing, which  will  be  made  clear  by  the  further 
discussion:  psychology  is  the  study  of  experience; 
of  the  reference  of  experience  to  its  content;  of  any 
direct  reference  which  it  may  have  to  a  subject  of 


INTRODUCTION  0 

experience;   and  of  the  content  of  experience  in  so 
far  as  it  is  directly  related  to  experience. 

2.  Terminology 

The  terms  used  in  this  book  may  at  first  be 
a  series  of  stumbling-blocks.  Not  only  will  the 
meaning  in  which  many  of  them  are  used  be  found 
to  differ  decidedly  from  the  meaning  attached  to 
them  in  every-day  language,  but  in  many  cases  the 
terms  are  not  used  in  the  senses  in  which  they  are 
used  in  other  books  which  will  be  read  by  the  stu- 
dent. This  confusion  is  unavoidable.  The  terms 
have  been  used  in  so  many  different  sciences  (to  say 
nothing  of  their  unscientific  uses),  that  they  have 
acquired  a  variety  of  meanings,  and  we  are  obliged 
to  select  the  significations  which  seem  most  appro- 
priate. Some  words,  such  as  "mind,"  "intelli- 
gence," and  "soul,"  have  had,  and  still  have,  so 
many  different  meanings  that  they  have  come  at  last 
to  mean  practically  nothing,  and  we  hesitate  to  use 
them  at  all  where  accuracy  is  essential.  In  the 
choice  of  the  signification  to  be  given  to  a  term  we 
should  be  guided  not  only  by  predominance  of 
present  usage  amongst  psychologists,  but  also 
by  the  historical  setting  of  words,  and  by  popular 
usage;  and  having  attached  a  given  signification  to 


6  A    SYSTEM   OF   PSYCHOLOGY 

a  term  we  ought  to  endeavor  to  adhere  to  it  through- 
out. 

The  term  "experience"  is  currently  used  in  two 
ways.  In  the  first  place,  it  means  to  know,  appre- 
hend, or  perceive  something;  as  when  I  say  I  ex- 
perience a  sound,  a  color,  a  pain,  or  an  emotion. 
In  the  second  place,  it  means  that  which  is  appre- 
hended or  directly  known,  that  is,  the  sound  which 
is  heard,  the  emotion  which  is  felt,  etc.,  are  called 
experiences,  or  kinds  of  experience.  There  has 
been  a  great  deal  of  shifting  back  and  forth  from  the 
one  of  these  meanings  to  the  other,  which  has  in- 
troduced deplorable  confusion;  and,  manifestly,  if 
we  wish  to  avoid  such  trouble  we  must  adopt  and 
cling  to  one  meaning.  We  shall,  therefore,  use  the 
term  in  the  first  sense  given  above;  to  designate  the 
being  aware  of  something,  and  not  that  of  which 
one  is  aware  (except  in  so  far  as  one  may  possibly 
be  aware  of  being  aware,  which  need  not  concern 
us  here  and  now).  This  first  meaning  is,  after  all, 
the  fundamental  one,  and  we  could  hardly  avoid 
using  the  term  in  this  way  even  if  we  used  it  also 
in  the  other. 

The  noun  "experience"  is  equivalent  to  the  word 
"  consciousness,"  and  we  shall  so  use  it,  and  shall  use 
the  verb  "to  be  conscious  of"  as  equivalent  to  "to 


INTRODUCTION  7 

experience."  "Consciousness"  meant  originally 
"the  knowing  that  one  knows,"  "the  experiencing 
that  one  experiences,"  to  which  we  above  referred 
parenthetically;  but  it  has  completely  lost  in  mod- 
ern psychological  usage  that  former  restriction  of 
meaning.  It  is,  however,  used  frequently  in  the 
sense  which  we  have  given  as  the  second  meaning 
of  experience,  namely:  that  which  is  apprehended 
or  known  directly.  Some  authors  with  due  notice 
use  the  term  in  both  senses,  and  others,  we  regret  to 
say,  make  similar  usage  without  notification.  Out- 
side of  psychology  the  historical  meaning  is  still 
in  vogue  to  some  extent,  and  the  resulting  misunder- 
standing may  be  readily  conceived. 

"Knowledge"  is  a  wider  term  than  "experience" 
or  "  consciousness,"  and  our  use  of  the  former  term 
in  defining  the  other  two  must  be  understood  with 
this  qualification.  It  is  only  direct  knowledge  as 
distinguished  from  indirect,  that  can  be  identified 
as  experience.  The  significance  of  this  distinction 
will  become  clearer  later. 

For  that  which  we  experience,  or  of  which  we  are 
conscious,  we  have  the  convenient  and  unambig- 
uous term  "content  of  consciousness"  or  "content 
of  experience."  Frequently,  however,  we  speak  of 
the  "objects"  of  consciousness  or  experience,  or  of 


8  A    SYSTEM   OF    PSYCHOLOGY 

"psychological  objects."  Thus,  the  sound  which  I 
hear  is  a  psychological  object,  as  distinguished  from 
the  air  vibrations  which  cause  it,  which  latter  are 
physical  objects,  and,  as  we  shall  see,  are  not 
heard  or  experienced,  although  we  may  know  of 
them. 

Other  terms  will  be  defined  and  explained  in  the 
sections  in  which  their  comprehension  can  be  made 
most  easy. 

3.  Extrinsic  Helps 

The  proper  preparation  for  the  study  of  psychol- 
ogy cannot  be  prescribed  in  a  way  that  will  cover 
the  needs  of  diverse  individuals.  One  student  will 
make  excellent  progress  while  lacking  certain  ad- 
vantages without  which  another  sticks  fast.  The 
elements  of  physics  and  of  anatomy  ought  to  be 
understood,  and  the  cell-physiology  which  is  given 
in  the  thorough  courses  in  elementary  biology  or 
physiology  is  of  value.  The  student  will  get  all 
he  needs  of  these  subjects  from  good  lecture  and 
demonstration  courses  in  them,  and,  if  after  his 
elementary  course  in  psychology  he  decides  to  follow 
it  farther  in  some  particular  direction,  he  will  then 
discover  in  which  of  the  sciences  he  needs  laboratory 
training.     Perhaps  the  greatest  need   for  the  be- 


INTRODUCTION  9 

ginner  is  an  adequate  training  in  literature,  which 
may  be  acquired  by  well-directed  reading;  for 
psychology  is  least  of  all  the  subject  in  which  any- 
thing can  be  communicated  or  comprehended  in  a 
special  jargon  or  terminology,  but  requires  all  the 
assistance  that  can  be  given  by  command  of  the  re- 
sources of  the  language  of  the  masters  in  letters  and 
of  the  speech  of  the  plainer  men.  After  literary 
training  we  should  rank  in  importance  a  knowledge 
of  physics  as  a  close  second. 

We  have  omitted  the  customary  anatomical  pict- 
ures and  discussions  from  this  book,  as  the  result 
of  deliberation  and  conviction.  Cuts  of  the  brain 
and  nervous  system  are  readily  accessible  to  any 
student  who  cares  to  look  at  them,  and  it  is  better 
for  him  to  be  sent  to  good  anatomies  to  consult  a 
hundred  pictures  than  to  have  a  dozen  or  so  chosen 
out  and  put  before  him.  Each  instructor,  more- 
over, has  his  own  choices  of  preparations,  models, 
charts,  slides,  and  cuts,  and  of  methods  of  presen- 
tation of  nervous  anatomy  and  histology.  A  super- 
ficial presentation  here  (and  none  other  could  be 
given  in  the  limits  of  this  book)  would  be  a  posi- 
tive detriment.  The  books  and  cuts  suggested  are 
merely  first  aid  to  the  student  working  alone. 

Piersol's  Human  Anatomy;  Howell's  Text-Book 


10  A    SYSTEM  OF   PSYCHOLOGY 

of  Physiology;  Quain's  Anatomy,1  vol.  I,  pt.  II,  and 
vol.  II,  pts.  II  and  III;  Schafer's  Text-Book  of 
Physiology,  vol.  II,  and  McKendrick  and  Snod- 
grass's  Physiology  of  the  Senses  are  all  valuable 
aids  in  understanding  the  schematic  anatomy  of 
the  nervous  system.  Excellent  plates  of  brain,  eye, 
and  ear  are  given  in  the  Sorbotta  McMurrich  Atlas 
and  Text-Boole  of  Human  Anatomy,  vol.  III.  We 
will  give  references  chiefly  to  Piersol  and  Quain, 
because  one  of  these  will  doubtless  be  accessible  to 
the  student.  No  specific  references  will  be  given 
to  McKendrick  and  Snodgrass  because  the  book  is 
small,  and  appropriate  material  easy  to  find  therein. 

As  for  the  general  principles  of  nervous  function, 
the  best  brief  account  is  found  in  Howell,  chaps. 
VI  to  XI,  inclusive.  The  account  of  the  nervous 
system  given  in  Piersol,  beginning  on  page  996,  is 
especially  valuable.  For  the  needs  of  students  of 
psychology,  however,  Part  First  of  Ladd  and  Wood- 
worth's  Elements  of  Physiological  Psychology  is 
without  doubt  the  best  available  general  treatise  on 
the  structure  and  functions  of  the  nervous  system. 

On  the  physical  problems  of  light  and  sound, 
the  articles  by  Lewis  and  Hallock,  respectively,  in 

1  The  references  are  to  the  tenth  edition  of  Quain,  and 
third  edition  of  Howell. 


INTRODUCTION  11 

Duff's  Text-Book  of  Physics,  will  be  found  element- 
ary and  useful.  Zahm's  Sound  and  Music  is  an 
intelligible  and  interesting  treatise  on  acoustics. 
Unfortunately,  the  more  commendable  treatises, 
such  as  Barton's  Text-Book  on  Sound,  are  too  tech- 
nical for  the  student  who  is  not  a  specialist  in  phys- 
ics. TyndalPs  Lectures  on  Sound  are  still  useful, 
and  Helmholtz's  Sensations  of  Tone  (Ellis's  trans- 
lation) is  the  starting-point  for  the  student  inter- 
ested in  the  psychology  of  audition. 


CHAPTER   II 

PRELIMINARY  ANALYSIS  OF  CONTENT 
I.  Complexity  of  Content  and  Complexity  of  Experience 

The  content  of  your  experience  at  any  given 
moment  in  your  life  history  is  exceedingly  complex. 
As  you  sit  reading  this  book  you  have  visual  im- 
pressions of  various  forms  and  colors  from  the  book 
and  from  surrounding  objects;  you  get  various 
sounds;  odors;  impressions  of  touch  from  the  book 
and  from  your  clothing  and  chair;  feelings  in  the 
muscles,  joints,  eye-sockets,  and  viscera.  All  these 
things  are  sensed  or  perceived,  and  simultaneously 
something  is  thought  of;  e.  g.,  the  meaning  of  this 
print  is  presented  as  a  content  of  thought.  Add  to 
these  factors  the  emotional  complexes  of  interest, 
weariness,  hunger,  satisfaction,  disgust,  annoyance, 
or  whatever  else  is  giving  "tone"  to  your  content, 
and  you  begin  to  see  the  truth  of  the  opening  sen- 
tence in  this  paragraph. 

Although  the  content  of  experience  is  demonstra- 
bly composed  of  a  multitude  of  parts  or  elements 

in  complicated  organic  interrelation,  it  does  not  fol- 

12 


PRELIMINARY   ANALYSIS   OF   CONTENT         13 

low  that  experience  itself  is  complex.  This  has  been 
a  stumbling-block  for  modern  psychology  because 
of  the  frequent  lack  of  clear  distinction  between 
consciousness  and  its  object.  It  is  often  said  that 
the  content  is  not  complex,  but  is  simple  and  uni- 
tary;  and  that  the  elements  into  which  we  apparently 
resolve  it  by  analysis  are  really  new  content  brought 
into  existence  by  our  analysis.  In  stricter  language, 
this  really  means  that  while  the  content  which  you 
apprehend  is  complex,  and  may  be  resolved  into  its 
elements,  the  apprehension  or  experience  of  the 
content  is  not  itself  a  complex  made  up  of  the  appre- 
hensions of  the  different  elements.  To  this  dogma 
there  is  so  far  no  reasonable  objection,  although  it 
may  be  found  ultimately  that  even  experience  is 
not  so  unitary  as  it  appears  to  be;  or  rather,  as  it 
suits  our  presuppositions  to  think  it  is. 

2.  General  Classification  of  Elements  of  Content 
In  the  examination  of  content  of  consciousness  it 
is  important  to  ascertain  as  definitely  as  possible 
how  many  sorts  of  elementary  content  there  are. 
By  elementary  content,  or  element  of  content,  we 
mean  that  portion  of  content  which  is  not  itself  com- 
plex; that  is,  which  cannot  in  turn  be  analyzed  into 
component  parts.     Of  such  elements  there  appear 


14  A   SYSTEM  OF   PSYCHOLOGY 

to  be  four  groups,  each  including  a  number  of  sub- 
groups. Further  investigation  may  show  that  at 
least  one  of  these  groups  must  be  fundamentally 
revised,  and  perhaps  eliminated,  but  we  must  give 
them  all  consideration.  These  four  kinds  of  con- 
tent are  sensations,  relations,  feelings,  and  images. 
We  will  indicate  briefly  in  the  next  paragraphs  what 
these  terms  cover. 

Sensations  are  such  things  as  color,  sound,  odor, 
and  warmth.  Look  at  a  drop  of  red  ink  on  a  paper 
before  you;  the  color — the  red — abstracted  from 
its  position  on  the  paper,  from  its  reference  to  other 
objects,  from  its  familiarity,  from  its  likeness  or 
unlikeness  to  other  colors;  in  short,  from  every- 
thing but  the  color  as  presented,  is  a  sensation.  So 
the  sweet  from  sugar  on  the  tongue,  abstracted  from 
all  the  attendant  impressions  in  the  mouth,  from 
the  fact  that  it  is  sugar,  from  the  pleasantness,  etc., 
is  a  sensation. 

It  is  one  of  the  commonplaces  of  psychology  that 
a  sensation  is  never  presented  alone  to  your  ex- 
perience. Neither  is  a  mere  group  or  complex  of 
sensations  ever  presented  alone  to  the  adult,  and 
probably  not  to  the  infant.  Always  there  are 
other  elements,  such  as  difference,  familiarity,  un- 
pleasantness, etc.,  joined    with    it.     Nevertheless, 


PRELIMINARY   ANALYSIS   OF   CONTENT         15 

we  can  pick  out  from  among  the  mingled  factors 
of  the  complex  the  sensation  itself  and  consider  it 
in  detail. 

Relations  are  easily  recognized,  or  at  least  some 
of  them  are.  Similarity,  difference,  sequence,  inter- 
mediacy,  possession,  etc.,  are  experienced  just  as 
directly  as  are  sensations.  Perhaps  the  instances 
given  are  not  simple;  perhaps  they  may  be  analyz- 
able  into  simpler  relations,  but  they  are  sufficiently 
good  specimens. 

Feelings  are  most  easily  identified  in  emotions 
or  passions.  Joy,  sympathy,  ennui,  rage,  hunger, 
pleasure,  are  contents  which  involve  complexes  of 
bodily  sensations,  relations,  and  in  addition  the 
feelings  which  are  their  most  important  character- 
istics. The  total  complexes  named  may  all  with 
fairness  be  called  emotions,  and  their  analysis  pre- 
sents probably  the  maximum  of  difficulty  with  which 
psychology  has  to  contend.  But  it  is  reasonable  to 
conclude  for  the  present  that  they  cannot  be  com- 
pletely accounted  for  without  taking  into  account 
elements  of  feeling.  If  it  should  eventually  be 
demonstrated  that  these  feelings  are  nothing  but 
specific  sensations,  we  will  have  neither  done  nor 
suffered  harm  by  listing  them  as  elements  or  quasi- 
elements. 


16  A    SYSTEM   OF   PSYCHOLOGY 

Images  are  generally  considered  as  being  the 
"copies"  or  "revivals"  of  sensations  and  of  com- 
plexes of  sensations  previously  experienced.  Hav- 
ing been  conscious  of  the  sensation  of  red  under  the 
influence  of  physical  light-waves  you  may  later  ex- 
perience an  "image"  which  is  in  some  respects  like 
the  sensation,  and  which  will  represent  it.  By  the 
images  of  sound,  color,  touch,  and  of  sensations  from 
the  muscles,  we  are  enabled  to  "think"  of  content 
which  is  not  present;  this  is  practically  the  doctrine 
as  Aristotle  handed  it  down,  and  it  is  the  doctrine  of 
current  psychology. 

We  regret  the  necessity  of  departing  radically 
from  established  opinion,  but  feel  the  obligation  to 
warn  our  readers  at  once  of  our  conclusion  that  the 
belief  in  the  existence  of  such  forms  of  content  is  a 
delusion,  flowing  partly  from  certain  peculiarities  of 
consciousness  and  partly  from  metaphysical  preju- 
dices. We  shall  present  the  case  in  detail  in  the 
proper  place,  not  slighting  the  current  theory. 

3.   Terminology 
In  contradistinction  to  content  imagined,  we  speak 
of  content  intuited  or  apprehended,  and  oppose  in- 
tuition   or    apprehension    to    imagination.     Thus, 
when  light-rays  fall  upon  my  retina,  I  intuit  a  light 


PRELIMINARY   ANALYSIS   OF   CONTENT         17 

sensation.  Sometimes  the  sensation  is  said  to  be 
present  as  opposed  to  a  sensation  or  other  content 
merely  imagined.  Perception  applies  to  intuition, 
and  to  intuition  plus  imagination;  usually  it  has 
the  latter  reference.  This  will  be  clear  to  the  reader 
after  he  has  studied  the  chapter  on  perception. 
Intuition  is  popularly  used  to  signify  an  occult  or 
inexplicable  awareness  of  some  fact;  it  is  needless 
to  say  that  as  we  use  the  word  it  has  no  shred  of 
that  meaning,  which  is  a  perversion  of  the  correct 
signification. 


CHAPTER    III 

SENSATION   IN  GENERAL 

i.  Sensation,  Physical  Stimulus,  and  Physiological 

Process 

Sensation — that  which  is  experienced  through 
the  senses,  or  through  sense — must  be  distinguished 
rigidly  from  the  physical  stimulus,  on  the  one  hand, 
and  the  nervous  activity  which  is  caused  by  this 
stimulus,  on  the  other  hand.  The  normal  stimulus 
is  some  activity  of  what  we  call  "matter,"  usually 
outside  of,  but  acting  on,  the  body  of  the  individual. 
Thus,  the  oscillation  of  the  air  particles  which  act 
on  the  inner  organs  of  the  ear  and  produce  sound; 
the  vibration  of  the  ether  which  stimulates  the  ret- 
ina of  the  eye  and  occasions  the  experience  of  light; 
the  chemical  activity  of  substances,  which  produces 
odor;  these  are  instances  of  stimuli.  There  is  little 
difficulty  in  distinguishing  stimuli  from  sensations, 
even  for  the  beginner,  for  a  little  reflection  convinces 
us  that  these  physical  facts  are  not  experienced, 
but  only  inferred.  When,  for  instance,  I  hear  a 
tone,    I   am   not   conscious   of   the   back-and-forth 

movement  of  the  air  particles;    and  when  I  see  a 

18 


SENSATION    IN   GENERAL  19 

color  I  am  not  experiencing  the  undulations  of  the 
ether.  In  the  latter  case  the  stimulus  is  so  far  from 
being  experienced  that  it  has  required  great  labor 
to  discover  its  real  nature  (assuming  that  we  do 
know  it  now)  by  inferences  from  observations,  and 
it  took  years  for  those  who  held  the  present  theory 
to  convince  of  error  those  who  drew  different  con- 
clusions from  the  observations.  Even  to-day  phys- 
icists do  not  profess  to  have  a  complete  under- 
standing of  the  actual  behavior  of  the  ether  and 
some  of  them  doubt  its  existence.  Yet  an  ignorant 
man,  who  has  never  heard  of  ether,  and  whose  views 
on  the  transmission  of  light  are  amusing,  may  ex- 
perience light  and  color  sensations  which  are  as 
highly  developed  as  those  of  any  one.  The  smell 
of  a  volatile  substance  depends  doubtless  on  the 
arrangement  of  the  atoms  in  the  molecules  (or  on 
some  such  physico-chemical  factor),  but  smell  itself 
gives  no  direct  information  as  to  this  arrangement. 
So  it  is  throughout.  What  you  experience  through 
the  senses  is  not  a  material  object,  or  any  part  of  a 
material  object,  although  we  have  learned  all  we 
know  concerning  material  objects  from  a  study  of 
the  behavior  of  sensations.  We  have  discovered  dur- 
ing the  last  ten  centuries  a  great  deal  about  the  phys- 
ical activities  corresponding  to  most  of  our  sensa- 


20  A   SYSTEM   OF   PSYCHOLOGY 

tions,  and  the  general  principles  of  their  behavior; 
which  helps  to  create  in  the  unreflective  the  belief 
that  we  experience  directly  the  physical  activities 
themselves. 

The  difference  between  the  sensation  and  the 
nervous  process,  especially  that  in  the  brain,  is 
harder  to  grasp  than  is  the  difference  between  sen- 
sation and  stimulus.  This  difficulty  is  at  once  ex- 
emplified and  increased  by  the  fact  that  many  physi- 
ologists seem  to  teach  that  there  is  no  difference. 

The  psycho-physiological  confusion  is  rendered 
well-nigh  hopeless  by  the  ambiguity  of  the  term 
"  nervous  process,"  and  though  the  ambiguity  is  not 
dangerous  in  physiology,  it  is  productive  of  much 
trouble  when  physiology  is  brought  into  relation 
with  other  studies.  The  terms  "brain,"  "nerve," 
etc.,  may  mean  the  actually  experiencible;  that  is, 
visible  and  tangible  objects;  and  "  nervous  process," 
accordingly,  may  signify  changes  which  may  act- 
ually be  watched,  or  which  might  be  observed  if 
sufficiently  delicate  instruments  were  available.  On 
the  other  hand,  the  terms  may  signify  the  matter 
and  material  changes  which  are  supposed  to  be  at 
the  basis  of  these  observable  things  or  changes,  and 
which,  of  course,  we  infer,  but  do  not  experience. 
If,  for  example,  someone  could  lay  bare  your  brain 


SENSATION'    IX    GENERAL  21 

and  with  proper  instruments  observe  the  operations 
of  that  mechanism,  his  sensations  would  be,  loosely 
speaking,  brain  processes;  at  least,  the  brain  proc- 
esses observed  would  be  partly  composed  of  his 
sensations.  But  this  is  not  what  the  physiologists 
mean;  they  mean  that  your  sensations,  while  you 
observe  anything  whatsoever,  are  identical  with  your 
brain  processes.  This  meaning  does  not  refer  to 
the  brain  processes  in  the  first  sense  mentioned, 
although  often  taken  in  that  way,  for  no  thoughtful 
person  would  be  guilty  of  supposing  that  while,  for 
instance,  you  are  watching  an  indigo  blue  light, 
that  shade  of  blue  could  be  discovered  by  obser- 
vation of  your  brain  cells.  In  general,  if  you  could 
watch  the  light  (or  other  object),  and  at  the  same 
time  watch  through  some  instrument  all  the  changes 
observable  in  the  brain  and  nerve  cells,  you  would 
find  practically  nothing  in  common  in  the  two  ob- 
jects. 

The  brain  processes  the  physiologists  mean  when 
they  say  that  a  sensation  is  a  brain  process  are  the 
material  facts  and  transformations  which  are  not 
observable  directly  as  brain  facts,  but  which  we  can 
infer;  in  short,  the  things  represented  by  the  sym- 
bols of  chemistry.  What  you  see,  when  you  ex- 
amine a  nerve,  are  only  sensations  of  light  and  color; 


22  A    SYSTEM   OF   PSYCHOLOGY 

what  you  feel  are  touch  sensations;  you  do  not  see 
or  feel  the  matter  of  the  nerve.  The  sensations 
you  experience  and  which  you  may  suppose  to  be 
the  nerve  under  examination  are  really  transforma- 
tions in  your  own  material  nerves,  which  cannot  be 
experienced  by  anybody  or  anything  except  your 
own  "  mind,"  or  perhaps  can  only  experience  them- 
selves. Thus,  the  sensation,  when  followed  relent- 
lessly back  in  the  physiological  system  of  events,  is 
apparently  found  to  have  disappeared  completely, 
and  to  have  been  replaced  by  something  else. 

The  vulgar  way  of  accounting  for  this  vanishing 
of  sensations  under  scientific  scrutiny  is  to  suppose 
that  the  "mind"  experiences  these  brain  changes 
and  experiences  them  (wrongly,  indeed,)  as  sensa- 
tions. This  is  merely  an  unintelligent  reversion  to 
an  older  and  more  respectable  theory — that  the 
processes  in  the  brain  produce  the  sensations  in  the 
"  mind," — which  theory  does  not  identify  the  process 
with  the  sensation.  A  more  modern  way  is  to  say 
that  the  brain  process  experiences  itself.  Thus,  we 
do  away  with  the  concept  of  "mind,"  except  as  a 
name  for  a  certain  activity  of  brain  cells  and  arrive 
at  a  point  of  view  which  is  apparently  quite  simple. 
But  this  little  subterfuge  saves  us  only  for  a  moment, 
and  either  method  of  explanation,  if  consistently 


SENSATION   IN   GENERAL  23 

adopted  and  carried  out,  lands  us  either  in  the  con- 
clusions of  the  Hindu  Vedantists,  that  the  world 
which  we  seem  to  experience  is  not  real  but  only 
illusion;  or  in  idealism,  which  holds  Mind  to  be 
the  only  reality.  If  we  wish  to  hold  to  the  theory 
that  there  is  a  real  world  to  experience,  we  must 
hold  that  sensation  is  not  brain  state  nor  brain  ac- 
tivity. 

The  student  will  probably  ask  himself — very 
likely  has  asked  while  reading  this  chapter — "  Where 
is  sensation?"  The  commonplace  answer,  "It  is 
in  the  brain,"  seems  to  commit  one  to  the  doctrine 
of  sensation  as  a  brain  state;  and  yet,  where  else 
can  the  sensation  be?  The  sensation  is  not  in  the 
brain  unless  the  whole  body  is  in  the  brain.  Sup- 
pose you  have  before  you  a  red  surface  and  ask  your- 
self, "Where  is  the  red?"  Put  your  finger  on  the 
surface,  and  the  evident  answer  is,  that  it  is  where 
the  finger  is;  that  is,  "out  there,"  in  space.  Of 
course,  there  is  a  possibility  that  you  are  deluded 
in  both  cases,  and  that  neither  the  color  nor  the 
finger  are  "there,"  but  are  both  in  the  brain;  or 
rather,  since  the  brain  itself  is  in  the  same  class  with 
the  finger,  the  whole  outfit  is  "  in  the  mind."  Thus, 
if  you  begin  by  assuming  that  the  sensations  are  in 
the  "mind,"  as  opposed  to  a  "real  world,"  you  will 


24  A    SYSTEM   OF   PSYCHOLOGY 

conclude  in  the  end  that  the  whole  knowable  uni- 
verse is  in  the  "mind,"  unless  you  are  too  busy,  too 
lazy,  or  too  dull,  to  carry  the  process  you  have 
started  to  its  logical  conclusion.  If  you  are  satis- 
fied, and  call  this  mental  universe  "  real,"  you  have 
reached  idealism.  If  you  are  dissatisfied,  and  think 
this  does  not  give  you  reality  enough,  you  have 
reached  the  Hindu  view  of  the  world  as  Maya,  or 
illusion.1 

We  do  not  feel  either  of  these  conclusions  to  be 
satisfactory,  and,  therefore,  are  forced  to  assume 
that  sensations  are  not  in  the  brain,  but  are  where 
they  are  experienced  as  being,  or  are  so  in  many 
cases.  In  some  instances  they  may  be  at  some 
other  point  of  space,  and,  hence,  wrongly  "lo- 
cated"; and  there  may  indeed  be  in  all  cases  a  cer- 
tain amount  of  error  in  location;  but  error  is  possible 
here,  as  elsewhere,  only  if  there  is  a  basis  of  correct- 
ness. 

If  it  should  be  proven  that  what  we  call  "out 
there"  is  really  in  the  mind,  then  our  analysis  is 
still  true,  for  the  sensation  is  "out  there"  in  so  far 
as  there  is  any  "out  there."     This  whole  matter  is 


1  If  sensations  are  brain  states,  or  "in  the  mind,"  so  are  all 
other  experiencible  elements  and  complexes;  and  we  expe- 
rience nothing  which  is  outside  the  brain  (or  mind). 


SENSATION    IN   GENERAL  25 

subject  to  many  sophistical  difficulties  which  it  re- 
quires clear  philosophy  to  dispel,  but  for  the  pres- 
ent the  student  need  not  abjure  his  naive  common- 
sense  view,  which  will  not  in  any  event  vitiate  his 
analysis,  whereas  the  opposite  view  certainly  would 
be  risky.  The  illusion  theory  and  the  idealistic 
hypothesis,  are  not  necessary  for  science  or  psy- 
chology. 

2.    Matter  and  Psycho-Physical  Causation 

Understanding  that  sensation  is  not  the  same 
thing  as  the  stimulus  which  may  physically  cause 
it,  and  is  not  the  same  thing  as  the  brain  and  nerve 
processes  which  may  also  be  said  to  cause  it,  we  still 
find  it  useful  and  necessary  to  treat  of  sensation 
and  other  mental  processes  in  relation  to  both  of 
these.  The  question  of  the  ultimate  relation  of  the 
mental  to  the  material,  with  its  more  or  less  def- 
inite answers  of  "parallelism,"  "interactionism," 
"materialism,"  etc.,  will  be  of  interest  and  impor- 
tance to  the  student  as  he  goes  deeper  into  psychol- 
ogy, but  are  so  far  from  being  essential  at  the  start 
that  a  considerable  knowledge  of  psychology  is 
necessary  before  he  can  take  up  these  matters  in- 
telligently. It  is  at  present  no  business  of  ours  to 
decide  whether  matter  actually  exists  as  substance, 


26  A   SYSTEM   OF   PSYCHOLOGY 

or  whether  it  is  only  a  convenient  fiction,  or  whether 
it  exists  in  the  Huxleyan  sense  as  the  universally 
valid  law  of  the  content  of  experience.  We  must 
hold  the  concept  of  matter  as  scientifically  indis- 
pensable,1 at  least  for  the  present,  and  take  it  into 
consideration  when  dealing  with  the  facts  of  experi- 
ence. The  author  is  personally  convinced  of  the 
correctness  of  Huxley's  theory,  which  has  the  weight 
of  centuries  of  philosophy  behind  it;  but  nothing  in 
the  present  volume  should  be  any  the  less  harmoni- 
ous with  your  postulates  if  you  hold  that  matter  is 
an  actual  thing  or  substance,  or  hold  some  other 
view;  because  none  of  our  psychological  analyses 
depends  on  any  such  assumption. 

On  the  other  question,  which  is  frequently  con- 
fused with  the  one  as  to  the  nature  of  matter  and 
its  relation  to  experiencible  things;2  on  the  ques- 
tion, that  is,  of  the  relation  between  the  experience 
and  its  content  and  the  brain  activities  which  ac- 
company this  experience,  and  which  may  them- 
selves be  made  the  content  of  experience,  we  must 
take  the  common-sense  view  that  the  relation  is  one 

1  By  "  matter"  is  meant  either  the  atoms  and  ether,  or  what- 
ever physical  science  replaces  these  with.  "Energy"  must 
also  be  included,  or  else  assumed  in  addition. 

2  This  confusion  furnishes  practically  the  whole  substance 
of  the  time-honored  dispute  between  the  "  interactionists " 
and  the  "  parallelists." 


SENSATION   IN   GENERAL  27 

of  cause  and  effect,  although  we  know  very  little 
about  the  real  nature  of  causation,  here  or  elsewhere, 
and  are  moreover  unable  to  find  out  just  how  the 
causal  sequences  occur  in  these  cases.  If  any  one 
is  prejudiced  the  other  way,  and  is  determined  to 
believe  that  there  is  no  causal  relation  between  brain 
and  experience,  he  will  probably  find  few  instances 
herein  in  which  our  supposition  makes  less  accept- 
able for  him  our  exposition  of  facts  and  principles. 

3.  The  Lag  of  Sensation 

The  sensation  may  or  may  not  begin  simulta- 
neously with  the  process  in  the  cerebral  cortex; 
there  is  no  direct  evidence  on  this  point.  Between 
the  initial  action  of  the  stimulus  on  the  end-organ, 
and  the  beginning  of  the  sensation,  there  is  an  in- 
terval whic  1  we  suppose  to  ba  due  primarily  to  the 
time  required  to  set  in  action  the  end-organ,  the 
nervous  path  of  conduction,  and  the  cerebral  ap- 
paratus successively.  When  the  stimulus  ceases  to 
act  on  the  end-organ,  the  sensation  does  not  cease 
at  once,  but  continues  for  a  brief  time;  this  per- 
sistence we  suppose  to  be  due  to  the  fact  that  the 
neural  apparatus  continues  in  action  after  the  dis- 
continuance of  the  stimulus. 

With  a  given  strength  of  stimulus,  the  time  re- 


28  A    SYSTEM   OF   PSYCHOLOGY 

quired  for  the  sensation  to  reach  its  maximal  in- 
tensity after  the  beginning  of  the  stimulus  is  less 
than  the  time  required  for  the  sensation  to  disappear 
after  the  cessation  of  the  stimulus.  The  time  re- 
quired to  raise  the  sensation  to  any  point  of  inten- 
sity lower  than  the  maximal  is  less  than  the  time 
the  sensation  will  last  after  it  reaches  that  same 
intensity  in  the  dying-out  process. 

The  delay  in  the  rise  of  the  sensation  to  a  maxi- 
mum, or  to  a  definite  point  below  the  maximum,  we 
designate  as  the  initial  lag  of  the  sensation.  The 
time  required  for  the  dying  out  of  the  sensation, 
from  the  point  at  which  the  stimulus  ceases,  is 
called  the  terminal  lag.  The  terminal  lag  is  greater 
than  the  initial  lag,  however  the  initial  lag  is  de- 
fined in  a  particular  case. 

We  take  practical  advantage  of  the  excess  of  the 
terminal  lag  over  the  initial  lag  in  the  mixing  of 
colors  by  means  of  revolving  discs.  If  the  disc  re- 
volves so  fast  that  the  retinal  processes  excited  by 
a  sector  in  any  retinal  area  do  not  diminish  appre- 
ciably in  intensity  before  the  sector  again  stimulates 
the  same  area,  the  effect  is  exactly  the  same  as  that 
of  a  constant  stimulus,  and,  therefore,  the  sensation 
is  steady.  The  initial  lag  operates  in  this  case  to 
effect  a  reduction  of  the  intensity  of  the  sensation 


SENSATION    IN    GENERAL  29 

below  that  which  would  obtain  if  the  stimulus  acted 
continuously.  The  passage  of  the  sector  across  the 
point  in  the  visual  field  occupies  so  brief  a  time  (if 
the  colors  blend  well)  that  before  the  physiological 
process  has  been  raised  to  its  full  intensity  the  sec- 
tor has  gone  by.  The  intensity  of  the  sensation 
produced  by  the  intermittent  stimulation  is  about 
the  same  as  the  intensity  produced  by  the  constant 
action  of  a  stimulus  bearing  the  same  intensity  ratio 
to  the  intermittent  stimulus  as  the  length  of  time 
the  intermittent  stimulus  is  present  bears  to  the 
total  time.1  This  generalization  is  known  as  the 
Talbot-Plateau  law.  Possibly  there  are  limitations 
to  be  made,  but  none  are  yet  established. 

The  other  modes  of  sense  are  theoretically  sub- 
ject to  lag,  and  its  occurrence  may  be  demonstrated 
in  the  cases  of  audition  and  the  dermal  senses. 
Where  the  intermittence  of  a  tone  is  rapid  enough, 
the  sensation  becomes  continuous  and  steady.    And 

1  For  example:  A  light  stimulus  which  is  so  intermitted 
by  means  of  rotating  sectors,  or  otherwise,  that  the  half- 
phase  from  disappearance  to  reappearance  is  exactly  as  long 
as  the  half-phase  from  reappearance  to  disappearance,  will 
appear  as  bright  as  a  stimulus  of  half  the  intensity  contin- 
uously present.  The  frequency  of  intermittence  necessary 
to  produce  a  "smooth"  mixture,  i.  e.,  to  avoid  nicker,  is  in 
many  cases  over  sixty  per  second;  with  dimmer  lights  a 
slower  rate  will  succeed.  This  rate  gives  us  no  idea  of  the 
actual  magnitude  of  either  initial  or  terminal  lag,  but  throws 
some  light  on  the  relation  of  the  two. 


30  A    SYSTEM   OF   PSYCHOLOGY 

a  rapid  succession  of  taps  on  the  finger  will  fuse 
into  a  steady  sensation. 

Intermittence  of  a  stimulus  modifies  in  an  essen- 
tial way  the  resulting  sensation  or  sensations.  This 
modification  is  in  some  circumstances  noticeable  in 
light  as  a  variation  in  quality,  but  is  still  more 
marked  in  the  case  of  tones,  because  a  large  part  of 
the  range  of  the  rates  of  sound  vibration  is  within 
the  range  of  intermittences  which  can  be  employed. 
The  practical  effect  of  intermitting  a  tone  stimulus 
is  to  add  to  the  sensation  another  tone  having  a 
pitch  corresponding  to  the  rate  of  intermittence, 
provided  the  said  rate  is  faster  than  circa  thirty  per 
second.  Below  thirty,  the  result  is  merely  the  pro- 
duction of  beats.  It  is  sometimes  said  that  the 
beats  "fuse  into  a  tone"  when  they  become  suf- 
ficiently rapid;  there  is  no  reasonable  objection  to 
that  form  of  statement  for  the  present.  The  new, 
or  secondary,  tone  arises  when  two  sources  of  sound 
differ  by  more  than  thirty  vibrations  per  second,  as 
well  as  when  a  single  tone  is  mechanically  inter- 
mittent; the  tone  in  the  one  case  mentioned  is  ac- 
cordingly called  a  difference  tone,  and  in  the  other 
an  intermittence  tone.  There  are  difference  tones 
of  the  first  and  second  orders,  corresponding  to  the 
two  orders  of  beats. 


SENSATION    IN    GENERAL  31 

The  production  of  a  tone  by  a  sound-wave  is 
itself  sometimes  spoken  of  as  the  fusion  of  the 
processes  aroused  by  intermittent  stimulation,  the 
sound-wave  being  considered  as  an  intermittent 
affair.  This  is  an  error,  for  the  sound-wave,  when 
rapid  enough  to  produce  a  tone  sensation,  is  strictly 
a  continuous  stimulus. 

4.  Secondary  Sensations 

In  many  cases  the  sensation  aroused  by  a  given 
stimulus  is  followed  by  a  secondary  sensational  con- 
tent, after  the  cessation  of  the  stimulus  in  question, 
and  without  further  essential  stimulation.  The  sec- 
ondary sensation  follows  its  primary  sensation  after 
an  interval  varying  from  a  fraction  of  a  second  to 
several  seconds.  It  may  be  of  the  same  quality  as 
the  primary,  or  it  may  be  of  some  other  quality  of 
the  same  mode. 

The  secondary  sensation  is  commonly  called  an 
"after-image,"  and  is  said  to  be  "negative"  when 
complementary  in  color,  or  opposite  in  temperature, 
to  the  primary  sensation,  and  "positive"  when  of 
the  quality  of  the  primary.  It  is  unfortunate  that 
we  have  not  a  better  terminology  for  these  phe- 
nomena, for  it  is  important  that  the  secondary 
sensations  be  distinguished  from  the  negative  after- 


32  A    SYSTEM    OF   PSYCHOLOGY 

images  described  in  the  chapter  on  sensation  qual- 
ity.1 The  true  negative  after-image  is  produced  by 
a  stimulation  which  may  be  called  secondary,  since 
it  follows  the  stimulus  which  conditions  the  pre- 
ceding sensation,  and  its  operation  depends  on  the 
results  of  that  stimulus;  but  as  a  sensation,  it  is 
just  as  primary  as  the  preceding  sensation. 

Secondary  visual  sensations  develop  best  after 
a  brief  stimulation  by  a  strong  light.  Gaze  for  a 
moment  at  a  gas  flame,  or  electric  light  filament, 
and  then  turn  out  the  light,  having  the  room  other- 
wise completely  darkened.  In  a  few  moments  an 
"image  of  the  light"  will  appear,  perhaps  in  its  nor- 
mal color,  perhaps  in  some  other;  it  may  seem  mi- 
nute in  size,  and  located  in  the  eye  itself;  by  a  little 
practice  you  can  succeed  in  projecting  it  to  a  dis- 
tance, when  it  will  seem  correspondingly  large.  A 
very  slight  movement  of  the  eye  will  cause  the  sec- 
ondary sensation  to  disappear  temporarily. 

5.  The  Characters  of  Sensation 

If  we  consider  a  single  sensation,  e .  g.,  a  certain 
red,  and  compare  it  with  others,  e.  cj.,  sweet  or  blue, 
we  find  that,  although  the  sensation  cannot  be 
analyzed  or  resolved  into  simpler  objects,  and,  there- 

•  Chap.  IV,  §  8. 


SENSATION   IN   GENERAL  33 

fore,  is  properly  called  elementary,  yet  it  is  not  so 
simple  that  it  has  not  several  different  aspects,  or 
points  of  difference  from  other  sensations.  These 
aspects,  or  points-  of  difference,  are  usually  called 
characters,  and  a  proper  understanding  of  these 
characters  is  the  indispensable  foundation  of  the 
study  of  sensation. 

In  the  first  place,  a  certain  red  differs  from  sweet 
and  blue  in  a  way  in  which  it  does  not  differ  from 
other  reds.  This  difference  we  call  one  of  quality. 
It  is  a  difference  in  kind  of  sensation.  Next,  there 
is  a  difference  between  certain  reds  of  the  same 
quality,  as  well  as  between  reds  and  any  other  sen- 
sations, which  we  call  intensity.  We  may  increase 
the  brightness  of  red  without  bringing  any  other 
eolor  or  sensation,  so  far  as  is  observable.  (In 
most  cases,  however,  changing  the  intensity  of  a 
color  involves  the  changing  of  the  quality  also,  to 
some  extent.)  A  spoonful  of  sugar  in  a  glass  of 
water  will  give  a  taste  which  is  weaker  (less  intense) 
than  two  spoonfuls;  and  though  we  commonly  say 
it  is  less  sweet,  we  do  not  mean  that  the  quality  is 
different,  but  that  the  intensity  is  less.1     The  weak 

1  The  same  language  in  regard  to  other  sensations  may 
mean  a  difference  of  quality,  rather  than  of  intensity.  Thus, 
to  say  a  light  is  less  red  than  another  usually  means  that  it 
contains  more  of  some  other  color. 


34  A   SYSTEM   OF   PSYCHOLOGY 

sweet  is  no  more  like  bitter  or  blue  in  quality  than 
is  the  more  intense  sweet. 

A  third  character  of  sensation  is  volume  or  ex- 
tensity.  A  large  patch  of  light  differs  from  a  small 
one  even  if  of  the  same  color  and  intensity.  So  a 
large  touch  on  the  skin  differs  from  a  small  one. 
Similar  differences  may  be  found  in  muscular  and 
auditory  sensations,  but  that  they  may  be  found  in 
all  kinds  cannot  be  said  definitely.  Smell  sensa- 
tions do  not  seem  to  have  this  character  at  all,  and 
its  presence  is  an  open  question  with  regard  to 
taste.  Extensity  is  sometimes  confused  with  ex- 
tension, or  perceived  space;  but  in  the  latter  the 
former  is  only  one  factor,  as  will  be  shown  in  the 
proper  place.  Extension  is  a  function  of  a  com- 
plex content,  but  extensity  is  just  as  original  an  as- 
pect of  those  sensations  which  possess  it  at  all  as  are 
quality  and  intensity. 

The  fourth  aspect  is  duration,  or  protenslty. 
Just  as  most  sensations  have  extensity  or  inchoate 
bigness,  which  forms  the  beginning  of  our  knowl- 
edge of  space,  so  all  have  a  magnitude  of  another 
sort  which  forms  the  basis  of  our  perception  of 
time.  No  sensation  can  be  conceived  which  has 
not  this  temporal  or  enduring  character.  It  may 
be  roughly  indicated  by  saying   that  a   sensation 


SENSATION   IN   GENERAL  35 

which  lasts  no  time  at  all  does  not  exist.  This, 
however,  gives  a  slightly  false  implication,  since 
the  protensity  of  a  perception  does  not  imply  the 
perception  of  time  as  such.1 

Some  sensations  possess  the  important  character 
of  local  significance.  Thi «  is  an  aspect  which  can- 
not be  directly  demonstrated,  but  which  can,  never- 
theless, be  conclusively  proved  to  exist.  It  is  the 
character  of  a  sensation  by  which,  independently 
of  its  other  aspects,  we  are  able  to  determine  the 
part  of  the  body  in  which  the  neural  process 
originates,  or  the  direction  in  space  from  which 
the  stimulus  comes.  The  sensation  from  each 
part  of  the  skin  and  retina  has  its  peculiar  local 
sign. 

Any  sensation  may  be  pleasant  or  unpleasant. 
By  considering  the  neutral  condition,  in  which 
there  is  neither  positive  pleasantness  nor  unpleas- 
antness, as  simply  the  transitional  point  between 
the  two,  we  may  consider  the  triad  as  an  aspect 
of  sensation  which  is  usually  called  feeling-tone. 
This  so-called  character  is  not  strictly  on  a  par  with 
the  ones  previously  enumerated,  because,  in  the 


1  Protensity  is  not  quite  the  same  as  duration,  in  the  com- 
mon acceptation  of  the  term.  This  will  be  made  clear  in 
the  section  on  time-perception. 


36  A    SYSTEM   OF   PSYCHOLOGY 

first  place,  it  can  be  considered  as  an  accompani- 
ment of  sensation,  which  the  others  cannot,  and  in 
the  second  place  it  is  equally  attached  to  other 
features  of  the  content  of  experience  besides  sen- 
sations, in  which  cases  it  seems  still  more  clearly 
to  be  an  accompanying  factor  rather  than  an  as- 
pect. 

The  characters  just  named  seem  to  exhaust  the 
list.  We  find  no  other  aspects  under  which  sensa- 
tion must  be  viewed  in  and  for  itself,  although  of 
course  we  find  it  functioning  in  definite  ways  in  the 
total  content,  and  entering  into  different  relations  to 
consciousness.  The  catalogue  stands  then :  quality, 
intensity,  protensity,  extensity,  local  significance, 
with  possibly  feeling-tone. 

In  an  advanced  study  of  the  psychology  of  sen- 
sation it  is  advisable  to  take  up  each  group  of 
sensations  by  itself,  and  to  give  it  exhaustive  treat- 
ment from  all  sides.  In  an  elementary  study, 
where  the  general  principles  are  more  important 
than  the  minute  details,  and  in  particular  where 
sensation  is  studied  in  its  connection  with  other 
content  and  with  experience  rather  than  for  its 
own  interest,  the  systematic  treatment  under  the 
different  aspects  or  characters  is  more  useful.  We 
shall,  therefore,  treat  sensation  first  under  its  qual- 


SENSATION    IN    GENERAL  37 

itative  aspect,  and  then  under  the  other  aspects  in 
order.  Such  a  programme  cannot  be  adhered  to 
absolutely,  and  there  will  necessarily  be  some  over- 
lapping. 


CHAPTER   IV 

SENSATION    QUALITY 
i.  General  Classification 

The  various  qualities  of  sensation  are  commonly 
divided  into  groups,  each  of  which  is  said  to  "  be- 
long to"  a  definite  sense.  Red,  green,  and  blue, 
for  example,  belong  to  the  sense  of  vision  and  are 
called  visual  sensations.  Bitter  and  sweet  belong 
to  the  sense  of  taste,  or  gustation,  and  are  called 
gustatory  sensations. 

It  is  sometimes  said  that  there  are  five  senses, 
but  as  a  matter  of  fact  we  discriminate  several 
more  than  that  number.  There  is  much  confusion 
in  regard  to  the  names  applied  to  several  of  the 
senses  and  to  the  sensations  which  appertain 
to  them,  and  still  more  confusion  in  the  names 
applied  to  the  sensibility  or  insensibility  to  certain 
sorts  of  sensation.  The  terms  given  in  the  follow- 
ing table  represent  the  most  justifiable  usage,  al- 
though not  in  all  cases  the  most  common: 

38 


SENSATION   QUALITY 


39 


THE  TERMINOLOGY  OF  SENSATION 


I 

II 

Ill 

IV 

V 

SENSE 

ADJECTIVES 

ANAESTHESIA 

Taste. 

Gusta- 
tion. 

Gusta- 
tory. 

Geusic. 

Ageusia. 

Smell. 

Olfaction. 

Olfactory. 

Osmic. 

Anosmia. 

Sight. 

Vision. 

Visual. 

Opsic. 

Anopsia. 

Hearing. 

Audition. 

Audit»ry. 

Acusic. 

Anacusia. 

Touch. 

Taction. 

Tactual. 

Haphic. 

Anaphia. 

Warmth-sense. 

Thalpotic. 

Athalposia. 

Cold-sense. 

Rhigotic. 

Arrhigosia. 

Tickle-sense. 

Titilli- 

Titilli- 

Gargal- 

Gargal- 

ation. 

atory. 

resthetic. 

anffisthesia. 

Muscle-sense. 

f 

Kinesthetic. 

Akina;sthesia. 

Joint-sense. 

Body-sense. 

Ccenfesthetic. 

Pain-sense. 

Algetic. 

Analgesia. 

Hair-sense. 

Tricho- 
a>sthetic. 

Tricho- 
anssthesia. 

Vibration-sense. 

Palmaesthetic. 

Paran- 
esthesia. 

The  first  column  contains  the  names  for  the 
senses,  derived  from  various  languages.  In  the 
second  column  are  the  corresponding  words  of 
Latin  derivation.  The  third  column  gives  the 
adjectives  applying  to  the  sensations.  In  a  case 
where  there  is  no  specific  adjective,  the  usual  Eng- 
lish sense  name  is  used  adjectively;  e.  g.,  pain 
sensation,  cold  sensation.  The  adjectives  from  the 
Greek,  given  in  the  fourth  column,  indicate  the 
sensibility,  and  should  not  be  used  to  indicate 
either  the  sense  or  the  sensation. 

The  prefixes  par-  (para-),  pseud-,  (pseudo-),  hyp- 
(hypo-),  and  hyper-  are  also  used  with  the  Greek 


40  A    SYSTEM   OF   PSYCHOLOGY 

words  (with  the  ia  termination)  to  indicate  specific 
aberrations  of  sensibility;  as,  for  example,  parop- 
sia,  pseudosmia,  hypokinoesthesia.  The  prefix  orth- 
(ortho-)  is  used  to  indicate  the  normal  condition  of 
the  sensibility,  as  for  example  orthacusia.  The 
suffix  -meter  is  added  to  indicate  the  instrument  for 
measuring  the  sensibility;  for  example,  aeumetcr, 
haptomctcr,  algesimctcr.  Certain  sense  realms  have 
also  special  prefixes  to  indicate  peculiarities  of  sen- 
sibility found  in  these  realms.  Chromopsia,  for 
example,  indicates  sensitivity  to  color;  achromopsia 
indicates  color-blindness;  and  for  various  aberra- 
tions of  color  sensitivity  we  have  the  terms  para- 
cliromopsia,  dichromopsia,  etc.1 

Each  sense  has  its  own  end-organ  or  organs; 
that  is,  some  mechanism  for  receiving  physical  stim- 
ulation and  transmitting  excitation  to  the  brain; 
this  is  true  both  anatomically  and  histologically. 
But  the  sense  cannot  be  defined  by  reference  simply 
to  the  organ  in  either  meaning.  Some  organs 
(grossly  speaking)  are  vehicles  for  more  than  one 

1  The  system  of  terminology  for  sense-psychology  given 
above  is  the  logical  one,  and  is  in  common  use,  except  for  the 
terms  for  temperature  sensations.  This  system,  however, 
is  not  exclusively  used,  there  being  the  most  deplorable  con- 
tusion in  regard  to  terms  for  almost  all  of  the  senses.  Cer- 
tain terms  are  used  by  different  authors  in  exactly  opposite 
senses,  and  for  some  cases  we  have  a  variety  of  terms  in  use. 


SENSATION   QUALITY  41 

sense.  The  eye  gives  visual,  muscular,  and  temper- 
ature sensations;  the  ear  auditory  and  organic  as 
well  as  tactual;  the  tongue  gustatory,  tactual,  and 
cold  and  warm  sensations;  the  nose  also  gives  tactual 
and  cold  and  warmth  as  well  as  olfactory  sensations; 
the  skin  gives  several  sorts  of  sensations. 

We  might  use  the  term  organ  in  a  narrower 
sense  and  say  that  the  retina  is  the  organ  of  vision, 
the  cochlea  the  organ  of  hearing,  etc.,  but  this 
would  be  inaccurate;  because  the  whole  ball  of  the 
eye  and  its  muscles  are  functionally  concerned  in 
vision,  and  form  the  organ;  and  so  likewise  the 
bones,  membranes,  and  muscles,  of  the  ear-drum 
are  entitled  to  be  specified  as  parts  of  the  organ  of 
hearing,  since  they  participate  normally  in  the  pro- 
duction of  the  nervous  process  which  conditions  the 
experience  of  sound. 

If  we  wish  to  associate  the  visual  sensation  with 
its  specific  nervous  terminals,  excluding  the  acces- 
sory parts  of  the  organ,  we  should  have  to  take,  not 
the  retina  as  a  whole,  but  the  minute  rods  and 
cones  therein,  into  consideration.  In  the  same  way 
we  should  consider  only  the  hair-cells  in  the  basi- 
lar membrane  of  the  inner  ear  in  connection  with 
auditory  sensations.  We  might,  therefore,  with  accu- 
racy  specify   visual  sensations  as  those  presented 


42  A   SYSTEM  OF   PSYCHOLOGY 

through  the  activity  of  the  nerve  endings  in  the 
retina  of  the  eye,  and  so  on;  and  to  this  method  of 
speech  there  can  be  no  reasonable  objection;  but 
it  gives  no  information  about  the  sensations  them- 
selves beyond  the  connection  explicitly  designated. 
It  neither  defines  nor  specifies  the  sensations,  but 
presupposes  their  identification. 

The  term  "  sense  "  is  used  very  loosely.  Some- 
times it  indicates  the  group  of  sensations,  sometimes 
the  abstract  possibility  of  experiencing  these,  and 
sometimes  the  entire  physiological  mechanism  for 
the  experience,  including  the  histological  organ. 
Accordingly,  psychologists  are  accustomed  to  use 
the  term  "mode  of  sensation"  to  convey  with  pre- 
cision the  first  of  these  meanings.  The  visual  sen- 
sations taken  as  a  group  are  said  to  constitute  the 
visual  mode  of  sensation;  the  olfactory  sensations 
the  olfactory  mode,  and  so  on.1  Modality  is  one 
step  above  quality  in  the  logical  classification  of 
sensations. 

1  Helmholtz  defined  a  mode  as  a  group  of  sensations  related 
so  closely  that  it  is  possible  to  pass  from  one  to  the  other  by 
a  gradation  so  minute  as  to  be  practically  continuous.  (Hand- 
buch  der  physiologischen  Oplik,  1894,  §  584.)  This  will  be 
illustrated  in  section  6  of  this  chapter,  in  the  case  of  visual 
sensations.  The  definition  is  not  useful,  since  it  gives  no 
criterion  for  distinguishing  a  transition  between  two  sensa- 
tions of  the  same  mode  from  a  transition  between  two  sen- 
sations of  different  modes;    hence  the  modality  has  always 


SENSATION   QUALITY  43 

2.  Sensation  and  Brain  Process 
Each  sensation  quality  depends  on  a  specific 
kind  of  nervous  process  in  the  cortex  of  the  brain, 
and  each  mode  of  sense  seems  to  be  dependent  upon 
the  functioning  of  a  definite  part  of  the  cortex,  which 
is  called  the  "  cortical  centre,"  for  that  mode.  Each 
mode,  and  perhaps  in  some  modes  each  quality,  is 
represented  by  certain  peripheral  nervous  structures 
called  "end-organs,"  and  these  are  connected  by 
sensory  nerves  with  the  corresponding  centres.1 

The  cells  of  the  sensory  cortex  are  specialized  to 
respond  to  the  excitations  poured  in  upon  them  by 
the  end-organs  with  which  they  are  connected. 
Whether  they  would  (in  the  case  of  an  adult)  re- 
spond to  a  different  kind  of  stimulation,  is  a  matter 
for  doubt.  In  the  plastic  condition  of  the  develop- 
ing cortex  (of  the  infant)  it  seems  to  be  a  fact  that 

to  be  distinguished  on  other  grounds.  A  continuously  graded 
transition  from  heat  to  bitter,  for  instance,  is  perfectly  possi- 
ble, and  there  would  be  no  objection  to  considering  it  a 
transition  within  a  mode,  if  we  had  not  decided,  on  grounds 
having  no  reference  to  the  question  of  gradations,  that  bitter 
belongs  to  one  mode,  and  heat  to  another.  The  final  deci- 
sion on  a  question  of  modality  of  elementary  sensations 
must  rest  on  the  likeness  and  unlikeness  of  the  sensations 
involved. 

1  See  Howell,  figs.  96-100,  and  pp.  198-228.  Piersol,  figs. 
102  and  1043;  also  figs.  1041,  1044,  909,  910,  987,  988. 
Schiifer,  figs.  330,  338,  340  and  351. 


44  A    SYSTEM   OF   PSYCHOLOGY 

if  certain  cells  which  would  normally  respond  to  a 
definite  sort  of  stimulation,  e.g.,  visual,  be  de- 
stroyed, other  cells,  either  in  the  cortex  or  in  the 
lower  centres,  may  become  so  adapted  as  to  respond 
to  that  sort  of  stimulus.  In  any  case,  it  is  the  kind 
of  stimulus  furnished  to  the  brain  cell  by  the  end- 
organ  which  determines  its  response.  Direct  irri- 
tation of  the  cells  of  the  cortex  by  electrical  currents, 
or  by  pinching  or  burning,  produces  no  sensation. 
The  character  of  the  process  in  the  end-organ  is  the 
thing  of  prime  importance  in  determining  the  sen- 
sory function  of  the  brain  cell. 

3.  Sensation  of  Taste 
Gustatory  sensations  are  dependent  on  the  stim- 
ulation of  certain  nerve  endings,  almost  all  of  which 
are  on  the  tongue.  These  nerve  endings  are  in  the 
"taste-buds,"  which  are  the  peripheral  organs  of 
taste.  They  are  found  on  the  tongue  in  the  walls 
of  the  circumvallate  papilla?  and  in  the  fungiform 
papilla?,  and  also  occur  in  the  epithelium  of  the 
mucus  membrane  where  there  are  no  papilla?.1  In 
the  cases  of  infants  and  some  adults  a  few  taste- 
buds  are  found  on  the  soft  palate,  gums,  cheek- 
linings  and  even  on  the  tonsils  and  hard  palate. 

•Piersol,  figs.   1193,  1194,  1195,  1196,  1197;    Quain,  III, 
pt.  Ill,  figs.  167,  168,  170,  172. 


SENSATION   QUALITY  45 

The  cortical  centres  for  taste,  or  gustatory  cen- 
tres, are  on  the  inner  sides  of  the  hemispheres, 
probably  in  the  hippocampal  lobes.  The  course  of 
the  nerve-fibres  from  tongue  to  cortex  is  extremely 
complicated.  One  bundle  runs  through  the  tym- 
panum (ear-drum),  and  is  hence  called  for  that 
portion  of  its  course  the  "chorda  tympani."  ' 

Substances  which  are  gustable  (sapid  substances) 
must  be  dissolved  in  water  (or  in  some  aqueous 
liquid;  saliva  is,  of  course,  the  common  solvent), 
and  so  either  enter  the  outer  part  of  the  taste-bud, 
or  perhaps  come  in  contact  with  the  hair-like  fibres 
of  the  gustatory  cells  projecting  into  the  orifice 
leading  to  the  bud.  Substances  insoluble  in  water 
are  tasteless;  but  soluble  substances  are  not  always 
gustable. 

Although  the  number  of  "flavors"  detectable  in 
substances  introduced  into  the  mouth  is  indefinitely 
large,  there  are  probably  but  four  distinct  element- 
ary taste  qualities.  These  are:  sweet,  salty,  bitter, 
and  sour  ("acid").  These  are  the  only  sensations 
(except  possibly  "metallic"  and  another  to  be 
noted  later)  referable  to  the  taste-buds,  and  are  the 
only  ones  to  be  called  tastes.  The  so-called  "al- 
kali" taste  is  probably  a  combination  of  weak  salty 
'Piersol,  figs.  1075  and  1079;    Howell,  fig.  119. 


46  A   SYSTEM  OF   PSYCHOLOGY 

with  weaker  bitter.  "  Hot "  tastes,  as  of  pepper,  are 
due  to  the  excitation  of  non-gustatory  end-organs 
on  the  tongue  and  in  other  parts  of  the  mouth,  and 
are  genuine  warmth  sensations,  like  those  obtain- 
able from  the  skin  of  the  hand  or  arm.  The  tongue 
is  also  sensitive  to  cold,  and  to  touch;  peppermint 
excites  indirectly  sensations  of  the  former,  and  "as- 
tringent"  substances,  as  alum  and  strong  tea,  ex- 
cite those  of  the  latter.  But  the  characteristic  thing 
about  what  we  call  flavor  in  foods  and  drink  is  given 
through  the  sense  of  smell,  as  may  be  demonstrated 
in  many  ways.  Every  one  has  noticed  the  com- 
parative tastelessness  of  food  during  the  course  of 
a  severe  cold;  this  is  the  result  of  the  interference 
of  the  catarrhal  inflammation  with  the  function  of 
the  organs  of  smell.  Conclusive  results  may  be  ob- 
tained readily  by  stopping  up  the  outer  opening 
of  the  nostrils  (anterior  nares)  and  the  inner  open- 
ing (posterior  nares).1  The  patient  then  breathes 
through  the  mouth  and  no  aroma  can  possibly  as- 
cend to  the  nostrils.  The  patient  in  the  condition 
described  is  temporarily  anosmic.     If  his  eyes  are 

1  The  posterior  nares,  of  course,  should  not  be  meddled  with 
except  by  a  physician.  But  one  can  obtain  fairly  good  re- 
sults by  stopping  the  anterior  nares  alone  (with  pieces  of 
cotton)  provided  the  patient  breathes  gently.  Vigorous 
breathing  increases  the  diffusion  of  odorous  substances  into 
the  nose  through  the  posterior  nares. 


SENSATION   QUALITY  47 

shut,  he  can  distinguish  substances  put  into  his 
mouth  only  in  so  far  as  they  differ  in  regard  to  the 
five  qualities  we  have  mentioned,  or  in  regard  to 
their  "feel"  (touch),  or  temperature.  A  few  in- 
stances will  illustrate.  Tea,  weak  coffee,  and  a 
solution  of  quinine  cannot  be  told  apart  if  the 
strength  of  each  is  properly  chosen.  If  the  tea  is 
very  strong,  the  quinine  solution  may  require  a  drop 
of  alum  water  to  be  added  to  it  to  make  it  taste  like 
the  tea.  Plain  sugar  and  water  cannot  be  distin- 
guished from  molasses  or  almost  any  fruit  syrup, 
properly  diluted.  Suitable  mixtures  of  grain  alco- 
hol and  water,  with  sugar,  and  a  few  drops  of  alum 
water  and  vinegar  (or  acid-solution),  as  necessary, 
will  counterfeit  vinous  or  distilled  liquors.  These 
experiments  may  be  extended  indefinitely,  and  not 
only  demonstrate  the  fewness  of  taste  qualities,  but 
will  also  show  how  very  sensitive  the  tongue  is  to 
touch  and  to  temperature,  and  how  much  our  dis- 
crimination depends  on  these.  It  is  well  not  to  let 
the  patient  taste  the  solutions  before  his  nostrils  are 
stopped,  or  slight  differences  in  viscosity,  or  strength 
of  any  element,  may  cause  him  to  remember  and 
distinguish  them  later,  with  no  intention  of  trickery 
on  his  part. 

The  functions  of  individual  taste-buds  have  not 


48  A    SYSTEM   OF   PSYCHOLOGY 

been  satisfactorily  examined,  but  experiments  which 
have  been  made  on  single  papillae  (fungiform)  show 
that  some  of  them  are  sensitive  to  two  qualities  only, 
some  to  three,  and  some  to  only  one,  although  there 
is  some  doubt  whether  there  are  papillae  sensitive 
to  bitter  only.  Seldom  are  papillae  sensitive  to 
all  four  qualities.  Whether  a  single  taste-bud 
can  produce  the  nervous  excitation  of  more  than 
one  taste  quality  is  for  the  present  an  open  ques- 
tion. 

The  circumvallate  papillae,  and  others  near  the 
base  of  the  tongue,  are  especially  sensitive  to  bitter. 
Papillae  sensitive  to  sweet  are  grouped  more  numer- 
ously toward  the  tip  of  the  tongue,  and  those  sensi- 
tive to  salt  and  sour  on  or  near  the  edges.  Sensi- 
tive papillae  are  few  in  the  central  area  of  the  tongue, 
which  some  experirnentors  have  reported  as  com- 
pletely ageusic;  but,  in  general,  all  parts  of  the 
upper  surface  of  the  tongue  possess  some  of  the 
papillae  sensitive  to  each  of  the  gustatory-  qualities, 
although  the  details  of  distribution  differ  with  the 
individuals,  and  some  persons  are,  through  disease, 
rendered  totally  ageusic. 

There  is  one  content  of  experience  which  is  com- 
monly called  a  "taste"  which  merits  special  atten- 
tion, since  it  is  not  included  in  any  of  the  conditions 


SENSATION   QUALITY  49 

we  have  here  described.  This  sensation,  or  com- 
plex, which  every  one,  no  matter  how  temperate, 
has  doubtless  experienced,  is  commonly  known  by 
the  picturesque  name  of  the  "dark-brown  taste." 
It  certainly  is  not  salt,  sweet,  or  sour,  and  the  bitter, 
metallic  or  astringent  components,  if  present,  arc 
not  the  main  thing.  Although  due  to  visceral  con- 
ditions, it  is  probably  produced  through  stimulation 
of  the  nerves  in  the  mouth,  and  so  may  have  a  cer- 
tain claim  to  be  classed  as  a  taste  sensation.  But 
there  are  other  reasons  why  it  may  be  classed  with 
the  organic  sensations  (ccenaesthesia),  and  we  shall 
discuss  it  further  under  that  head. 

4.  Sensations  of  Smell 

If  the  student  looks  on  the  nose  as  the  organ  of 
smell,  with  no  further  idea  of  the  exact  part  of  the 
nose  which  is  sensitive,  he  will  be  somewhat  sur- 
prised upon  examining  the  nasal  structure.  The 
interior  of  the  nose  is  a  complicated  cavern,  or 
rather  two  caverns,  communicating  not  only  with 
the  outer  air  and  with  the  pharynx,  but  with  cavi- 
ties in  the  bones  of  the  face.  The  peripheral  ner- 
vous apparatus  of  smell  occupies  only  a  very  small 
area  in  the  membrane  covering  a  part  of  the  supe- 
rior turbinal  bone  and  of  the  adjacent  portion  of  the 


50  A    SYSTEM   OF   PSYCHOLOGY 

nasal  septum.  This  region  is  known  as  the  olfac- 
tory region,  and  this  portion  of  the  membrane  as 
the  olfactory  membrane.  The  cells  which  receive  the 
terminations  of  the  nerve  fibres  are  much  like  the 
gustatory  cells  of  the  taste-buds.1 

The  fibres  of  the  olfactory  nerve  penetrate  di- 
rectly through  the  skull  to  the  olfactory  lobes  of  the 
brain,  and  pass  thence  to  the  hippocampal  lobe, 
especially  the  distal  portion  thereof,  called  the  gyrus 
uncinatus.  This  is,  therefore,  the  cortical  centre 
for  smell — the  olfactorv  centre. 

In  order  that  it  may  be  smelled,  a  substance  must 
be  in  a  gaseous  state,  and  must  be  brought  into 
direct  contact  with  the  olfactory  membrane.  How- 
ever fine  may  be  the  particles  of  a  substance,  if  they 
remain  mere  particles,  not  becoming  vaporized,  they 
are  without  odor.  Formerly  it  was  thought  that 
substances  dissolved  in  water  could  be  smelled  if 
brought  in  contact  with  the  membrane,  but  now  it 
is  known  that  such  is  not  the  case.  Substances 
that  are  odorous  also  fulfil  a  definite  chemical  con- 
dition;   the  molecules  which  constitute  them  must 


1  On  nose  and  peripheral  terminations  see  Piersol,  figs. 
1174,  1175,  1176,  1178,  1179,  1180;  Quain,  III,  pt.  Ill,  figs. 
154,  156,  157,  158,  159,  160;  Schiifer,  figs.  446,  447.  On  the 
neural  connections,  Piersol,  figs.  1042,  1043,  1047,  1048,  1049; 
Howell,  fig.  95;  Schiifer,  figs.  351,  349. 


SENSATION   QUALITY  51 

possess  or  exceed  a  certain  minimum  weight.  This 
minimum  is  for  most  persons  the  weight  of  prussic 
acid  (hydrocyanic  acid),  which  substance  is  odor- 
less for  these  individuals.  Other  persons,  whose 
osmic  sensitivity  extends  slightly  lower,  find  that 
prussic  acid  has  a  distinct  odor. 

Constant  presence  may  render  any  substance 
odorless;  that  is,  an  odor  continuously  present, 
finally  disappears.  Water  vapor  and  carbon  di- 
oxide, although  gaseous  and  of  sufficient  molecular 
weight,  are  odorless  because  always  in  the  air. 
This  is  probably  an  instance  of  what  is  best  desig- 
nated as  protective  adaptation.  A  sensory  organ 
acted  upon  by  a  stimulus  which  it  is  functionally 
fitted  to  receive  becomes  by  the  action  of  the  stim- 
ulus less  responsive  to  it.  This  is  not  fatigue,  which 
of  course  may  produce  a  similar  result;  it  is  an 
antagonistic  reaction  by  which  the  organ  becomes 
protected  against  the  action  of  the  stimulus,  just  as 
the  soles  of  the  feet  become  protected  by  thicken- 
ing of  the  skin  when  no  shoes  are  worn.  The  quick- 
ness and  completeness  with  which  one  becomes 
insensitive  to  an  osmic  stimulation  is  a  matter  of 
common  observation.  The  air  in  the  room  be- 
comes fetid  from  one  of  a  number  of  causes,  and 
you  do  not  notice  it  until  you  return  after  being 


52  A    SYSTEM   OF    PSYCHOLOGY 

out  of  the  room  some  moments.  People  are,  in 
general,  immune  to  the  odor  of  their  own  per- 
spiration. 

The  number  of  elementary  olfactory  qualities  is 
at  present  unknown.  We  are  obliged  to  treat  them 
as  if  they  were  indefinitely  numerous,  and  yet  there 
may  be  really  only  a  few,  which  by  combination  in 
endlessly  different  ways  give  rise  to  the  riotous  pro- 
fusion of  odors  which  constitute  our  olfactory  world. 
The  suggestive  similarities  which  run  criss-cross 
through  this  world  point  to  this  theory,  but  so  far 
we  have  not  been  able  to  make  any  scientific  use 
of  those  similarities.  Classification  by  qualitative 
affinity  has  been  attempted;  a  great  many  natural- 
ists since  Aristotle  have  tinkered  with  the  problem; 
the  most  laudable  attempt  being  made  by  the  bot- 
anist Linnaeus,  to  whose  catalogue  Zwaardemaker 
has  added  two  more  titles.  The  result  of  all  these 
efforts  has  been  of  slight  value  theoretically  or  practi- 
cally. The  classes  of  Linnaeus  are  nicely  exempli- 
fied by  certain  odors,  but  when  you  attempt  to 
classify  a  large  number  of  odors  according  to  the 
scheme,  you  find  that  many  belong  equally  well 
under  two  or  more  headings,  and  others  refuse  to  fit 
anywhere.  The  types  selected  evidently  do  not 
represent  anything  fundamental. 


SENSATION    QUALITY  53 

LINN.EUS'    OLFACTORY    CATEGORIES.       EXAMPLES 

1.  Aromatic Turpentine;  lavendar;  camphor;  spices; 

butyric  ether. 

2.  Fragrant Flowers;  vanilla;  benzoin. 

3.  Ambrosiac Musk;  ambergris. 

4.  Alliaceous Garlic;  assafcetida;  CI.;  Br;  CS2. 

5.  Hircine Cheese;  sweat;  rancid  oil;  lactic  acid. 

6.  Repulsive,  or 

Virulent Opium;  nightshade  family. 

7.  Nauseous Decaying  animal  matter. 

zwaardemaker's  additions 

a.  Ethereal Fruits;   some  essential  oils  and  ethers. 

b.  Empyrheumatic.  .Toast;  tobacco  smoke;  tar;  coffee;  gas- 

olene; creosote. 

Although  the  attempt  at  classification  has  been 
a  failure,  some  hope  has  been  aroused  by  the  dis- 
covery, by  Sir  William  Ramsay  and  others,  that  cer- 
tain substances  with  similar  molecular  structure 
have  similar  odors,  and  that  in  a  group  of  substances 
of  similar  structure  (as  the  alcohols)  the  pungency  of 
the  odor  increases  with  the  molecular  weight.  Al- 
though there  are  exceptions  enough  to  make  the 
connections  merely  interesting  and  suggestive,  it 
seems  certain  that  in  sensations  of  smell  we  come 
closer,  so  to  speak,  to  the  unexperiencible  matter 
than  in  sensations  of  any  other  mode. 

Individuals  differ  in  their  sensitiveness  to  odors 
even  more  than  they  do  in  regard  to  taste.  Some 
persons  are  osmically  as  keen  as  the  lower  animals; 


54  A    SYSTEM   OF   PSYCHOLOGY 

others  are  very  obtuse  to  odor,  and  some  are  com- 
pletely anosmic  from  birth.  Catarrh,  or  other  dis- 
ease, may  largely  or  completely  rob  the  victim  of 
his  sense  of  smell.  Other  details  of  osmic  sensi- 
tiveness will  be  mentioned  under  intensity. 

5.  Visual  Sensations 

The  nerve  endings  which  condition  the  produc- 
tion of  visual  sensations — the  rods  and  cones — are 
in  the  retina,  the  lining  of  the  eyeball.  The  other 
parts  of  the  eye  are  important  as  means  for  the 
bringing  of  the  rays  of  light  to  bear  properly  on 
those  endings.1 

The  fibres  of  the  optic  nerve  pass  from  the  rods 
and  cones  through  the  midbrain  beneath  the  hem- 
isphere to  the  occipital  lobes,  the  rearmost  portions 
of  the  hemispheres;  and  these,  with  the  addition  of 
certain  contiguous  areas,  constitute  the  visual  cen- 
tres.2 

Opposite  to  the  pupil  of  the  eye  there  is  a  little 
depression  in  the  retina,  about  two  and  one-half 
square  millimetres  in  area,  called  the  fovea.  While 
not  so  sensitive  to  light  as  are  the  surrounding  areas, 


1  Piersol,  figs.  1202,  1203,  1214,  1218,  1220,  1221,  1222,  1223; 
Quain,  figs.  45,  48,  52. 

-  Piersol,  fig.  1050;    Howell,  figs.  91,  92. 


SENSATION   QUALITY  55 

it  is  capable  of  finer  discriminations;  or,  as  we  say, 
the  visual  acuity  is  greatest  here;  hence,  the  eye  is 
commonly  moved  so  that  the  image  of  whatever  we 
are  attending  to,  or  the  most  important  part  of  that 
image,  falls  on  the  fovea.  Only  after  considerable 
practice  can  one  attend  to  a  definite  part  of  the  field 
of  vision  without  automatically  turning  the  eye  to- 
ward it  so  that  its  image  falls  on  the  fovea.  The 
fovea  contains  no  rods,  but  only  cones,  and  they 
are  here  covered  by  a  thinner  layer  of  nervous  tis- 
sue than  elsewhere,  so  that  the  light  reaching  them 
is  less  dispersed,  i.  e.,  is  brought  to  a  sharper  focus 
here  than  elsewhere  on  the  retina. 

A  short  distance  from  the  fovea  is  the  spot  at 
which  the  optic  nerve  enters  the  eyeball.  This  spot 
is  insensitive  to  light  because  there  are  here  neither 
rods  nor  cones,  and  is  hence  called  the  blind-spot. 
The  blind-spot  does  not  inconvenience  us  in  ordi- 
nary vision  because  it  is  so  situated  in  the  retina  that 
the  portion  of  the  image  which  falls  on  the  blind- 
spot  of  one  eye  does  not  fall  on  the  blind-spot  of  the 
other. 

We  can  discuss  color  only  by  reference  to  the 
solar  spectrum,  and  the  student  should,  if  possible, 
examine  the  spectrum,  either  projected  on  a  screen 
or   viewed    through    a    spectroscope.     Failing    the 


56  A    SYSTEM   OF    PSYCHOLOGY 

actual  spectrum,  colored  charts  of  it  may  be  used. 
Several  such  charts  are  published  but  are  not  chro- 
matically true. 

The  prism  of  the  spectroscope  spreads  out  the 
light-waves  coming  through  a  narrow  slit  into  a  di- 
verging beam  at  one  side  of  which  there  are  long 
waves  and  at  the  other  short  waves,  the  wave  length 
in  the  intermediate  portions  varying  accordingly. 
If  now  this  beam  of  light  falls  on  the  retina  through 
proper  lenses,  or  after  being  intercepted  by  a  screen, 
a  band  of  colors — the  "  spectrum  " — is  formed,  rang- 
ing from  the  red  produced  by  the  least  frequent 
(longest)  waves,  through  the  orange,  yellow,  green, 
blue,  to  the  violet  of  the  most  frequent  (shortest) 
rays;  and  as  the  wave  length  decreases  continuously 
from  one  end  of  the  spectrum  to  the  other,  so  the 
red  merges  smoothly  into  the  orange,  the  orange 
into  the  yellow,  and  so  on,  through  the  intermedi- 
ate hues  of  orange-red,  red-orange  yellow-orange, 
orange-yellow,  etc.  Here  we  have  an  excellent 
example  of  a  sensation-continuum;  a  series  of  sen- 
sations passing  one  into  the  other  without  discrete 
gradations;  that  is,  without  break. 

Although  there  are  a  great  number  of  hues  in  the 
spectrum,  there  are  only  a  few  elementary  color  sen- 
sations, and  the  other  hues  are  composed  of  these 


SENSATION   QUALITY  57 

in  different  proportions.  That  such  uniform  grada- 
tions can  be  produced  by  mixture  is  clearly  shown 
by  mixing  the  light-rays  from  the  ends  of  the  spec- 
trum, in  which  case  a  continuous  gradation  of  pur- 
ples is  obtained,  ranging  from  the  spectral  red  to  the 
spectral  violet:  a  series  which  is  not  in  the  spec- 
trum, but  which,  with  the  spectral  hues,  makes  the 
total  of  colors  within  our  experience. 

Inspection  shows  that  the  orange  is  a  composite 
color  involving  red  and  yellow;  that  the  hues  be- 
tween green  and  blue  are  really  only  blendings  of 
green  and  blue;  and  so  the  sensation-continuum 
here  is  not  different  in  kind  from  the  series  of  blend- 
ings of  bitter  and  sweet,  sweet  and  sour,  etc.,  al- 
though it  is  more  readily  displayed.  We  are  jus- 
tified, therefore,  in  assuming  that  there  are  a  few 
fundamental  colors,  just  as  there  are  a  few  tastes, 
and  that  the  combination  of  these  produces  all  the 
hues  with  which  we  are  familiar.1  In  seeking  for 
these  fundamental  colors  we  reject  the  orange,  the 


'It  is  sometimes  said  that  a  "mixed"  color,  e.  g.,  orange, 
does  not  contain  other  colors  (red  and  yellow,  in  case  of 
orange),  but  merely  is  like  them,  being  really  as  simple  as 
they  are.  On  this  postulate  a  psychology  of  color  has  been 
built  up,  but  has  so  far  not  justified  itself.  We  think  it  much 
more  rational  to  proceed  on  the  simpler  postulate,  on  which 
all  advance  in  the  knowledge  of  color  theory  is  actually 
founded. 


58  A    SYSTEM   OF   PSYCHOLOGY 

blue-greens  and  green-blues,  the  yellow-greens  and 
green-yellows,  and  the  extreme  violet  as  being  ap- 
parent mixtures.  We  have  left  as  presumably  fun- 
damental colors:  red,  yellow,  green,  and  blue  or 
violet-blue;  and  these,  or  certain  specific  portions 
of  them  in  the  spectrum,  seem  to  be  truly  element- 
ary. But  in  the  consideration  of  them  two  peculiar 
circumstances  are  at  once  discovered,  which  merit 
careful  attention. 

In  the  first  place,  there  is  no  direct  qualitative 
transition  between  the  red  and  the  green,  and  none 
between  blue  and  yellow.  That  is  to  say:  while 
you  may  arrange  between  red  and  blue  a  continuum 
involving  only  these  two  colors  (the  red-blues  or 
purples);  and  between  blue  and  green  a  similar 
continuum  of  green-blues  and  blue-greens;  and 
between  green  and  yellow  a  continuum  of  green- 
yellows  and  yellow-greens;  and  between  yellow  and 
red  a  continuum  of  yellow-orange,  orange,  etc.,  the 
yellow-blues  and  the  red-greens  are  lacking.  The 
transition  in  either  case  involves  one  of  the  other 
supposedly  elementary  colors,  or  else  white  (gray). 
We  can,  for  example,  pass  from  red  through  orange 
and  yellow,  or  through  purple  and  blue,  or  through 
pale  red  (pink),  gray,  and  pale  green;  but  never 
through  red-greens.     Yet,  if  red  and  green  are  ele- 


SENSATION   QUALITY  59 

mentary  colors  we  surely  ought  to  be  able  to  com- 
bine them  as  well  as  any  other  pair.  This  at  once 
suggests  that  the  four  colors  are  not  on  the  same 
plane. 

In  the  second  place,  the  combination  of  green 
rays  and  red  rays  in  diverse  proportions  (as  regards 
intensities)  gives  the  transition  colors  through  yellow, 
while  analogous  combinations  of  yellow  and  blue 
rays  produce  the  transition  colors  through  white 

(gray)- 

These  relationships  lead  to  the  conclusion  (first 
formulated  as  a  scientific  theory  by  Thomas  Young), 
that  yellow  is  not  an  elementary  color,  but  is  really 
red-green,  and  that  gray  is  the  composite  of  the 
three  elementary  colors,  red,  green,  and  blue  (or 
indigo).  This  is  the  so-called  "  Three-Color  Theo- 
ry," or  "Young  Theory" — often  called  the 
"Young-Helmholtz  Theory."  According  to  it,  the 
three  colors  are  supposed  to  depend  each  on  a 
specific  process  in  the  retina  and  in  the  brain  (chro- 
moptic  process)  the  nature  of  which  is  unassigned; 
and  each  of  these  three  processes  is  supposed  to  be 
excited  by  light  from  all  parts  of  the  solar  spectrum, 
but  most  strongly  from  one  particular  region  (see 
fig.  5).  The  yellow  portion  of  the  spectrum  is  so 
colored  because  the  rays  from  that  portion  excite 


60  A    SYSTEM   OF   PSYCHOLOGY 

both  the  red  and  green  processes  rather  strongly; 
while  the  rays  from  the  blue-green  portion  excite 
both  the  blue  and  the  green  processes  strongly. 

This  theory,  as  it  has  been  developed  by  Helm- 
holtz  and  others,  succeeds  in  referring  to  one  logical 
scheme  all  the  facts  of  visual  sensation  yet  discov- 
ered; but  in  its  looser  statement  it  has  encountered 
one  serious  criticism.  This  criticism  is  that  yellow 
cannot  be  introspectively  analyzed  into  red  and 
green,  and  gray  into  red,  green,  and  blue.  Exam- 
ine pure  yellow  as  intently  as  you  may,  and  you  can- 
not find  any  red  or  green  in  it,  and  gray,  if  it  is  pure, 
is  ipso  facto  neither  reddish,  greenish,  nor  bluish. 
This  consideration  has  led  many  physiologists  and 
psychologists  to  hold  to  the  theory  of  Hering,  or 
to  variants  of  his  theory.  They  hold  that  there 
are  four  colors — and  four  retinal  processes,  with  an 
additional  process  for  white.  They  even  assert  that 
black  is  an  elementary  sensation,  and  assign  a  sixth 
retinal  process  to  it.  These  six  processes  are  in  pairs, 
the  members  of  each  pair  opposing  each  other. 
We  cannot  go  into  the  details  of  this  theory, 
or  the  many  objections  to  it.  It  is  a  noteworthy 
fact  that  the  practical  working  out  of  the  theory 
obliged  its  adherents  to  abandon  the  very  psycho- 
logies! grounds  on  which  they  started,  by  assuming 


SENSATION   QUALITY  01 

as  a  fundamental  color  cither  blue-green  or  reddish- 
purple.1 

The  three-color  theory,  as  first  proposed,  implied 
the  composite  nature  of  the  sensations  of  white  and 
gray,  and  assumed  that  a  "color-blind"  (see  below) 
person  lacked  one  or  two  of  the  three  processes.  As 
a  matter  of  fact,  the  first  point  is  not  essential  to 
the  theory;  for  all  that  is  necessarily  assumed  is 
that  when  the  "red"  process  and  the  "green"  proc- 
ess are  active  together  at  certain  relative  intensities, 
the  sense-content  yellow  arises.  So,  the  theory  need 
not  insist  on  white  as  a  complex,  but  may  allow 
the  alternative  opinion.  That  is  to  say;  the  three- 
color   theory   is   not   necessarily  a   three-sensation 

theory- 

In  behalf  of  the  three-sensation  theory,  however, 
it  must  be  said  that  the  fact  that  a  content  of  ex- 
perience cannot  be  directly  analyzed  does  not  prove 
it  to  be  simple.  Of  course  we  may  assume  such  to 
be  the  case,  and  a  certain  sort  of  psychology  does 
make  that  assumption  to  cover  certain  convenient 
cases.  If  the  assumption  were  applied  in  a  thor- 
ough-going way  it  would  make  psychological  analy- 


1  For  further  details  of  the  Hering  theory  see  Rivers, 
(Schafer),  pp.  1112-1121.  On  the  Young  theory,  idem, 
1106-1112. 


62  A    SYSTEM   OF   PSYCHOLOGY 

sis  impertinent,  to  say  the  least,  and  experimental 
psychology  is  based  on  the  denial  of  this  assumption. 
As  for  color-blindness,  whatever  the  earlier  ad- 
herents of  the  theory  may  have  held,  the  present 
adherents  hold  that  in  the  common  cases  of  color 
abnormality  the  three  processes  are  present,  but 
have  an  unusual  range  of  excitability,  as  will  be 
explained  later,  although  it  may  be  that  in  some 
cases  there  may  be  one  or  more  of  the  processes 
lacking.1 

6.  The  Schematic  Representation  of  Visual  Qualities 

The  whole  range  of  color  hues  may  be  repre- 
sented (as  they  might  actually  be  presented)  in  the 
following  way.  Suppose  three  circular  patches  of 
light  partially  superposed  as  in  fig.  1.  Let  one 
patch  of  light  be  of  each  of  the  three  fundamental 
colors,  and  let  the  intensity  of  each  patch  be  maxi- 
mal at  its  centre,  falling  off  gradually  to  zero  at  the 
edge.  We  have  then  in  the  triangle  of  which  N  is 
the  centre  (leaving  now  out  of  account  all  the  un- 

'The  three-color  theory  in  the  five-sensation  form  has  been 
given  an  evolutionary  setting  by  Mrs.  Franklin,  who  assumes 
that  gray  is  the  primitive  color  phylogenetically;  that  in  the 
second  stage  of  development  yellow  and  blue  arise  by  a  dif- 
ferentiation of  the  "gray-process"  into  two  new  processes, 
and  that  in  the  third  stage  red  and  green  arise  by  a  differ- 
entiation of  the  "yellow-process." 


SENSATION   QUALITY  63 

superposed  and  two-ply  parts)  all  the  colors,  rang- 
ing from  the  full  hues  along  the  boundaries,  through 
paler  tints,  to  neutral  gray  or  white  near  the  centre. 
This  representation  introduces  us  at  once  to  a 
characteristic  of  color  sensations  which  is  desig- 
nated saturation.     A  color  is  said  to  be  saturated  in 


Fig.  1.  Fig.  2. 

proportion  as  it  does  not  contain  white  or  gray;  the 
more  gray  the  color  contains  (that  is,  the  paler  it  is), 
the  less  the  saturation  is  said  to  be. 

If  we  suppose  the  three  fundamental  colors  to  be 
taken  in  their  maximal  saturation,  we  can  represent 
all  visible  hues  in  every  possible  saturation  by  such 
a  triangle  as  that  in  fig.  1,  in  which  the  pure  funda- 
mentals stand  at  the  vertices.  For  convenience  we 
draw  the  sides  of  the  triangle  straight,  as  in  fig.  2; 
but  it  must  be  understood  that  the  exact  form  of  the 
triangle  is  insignificant — the  fact  that  we  have 
drawn  it  isosceles  does  not  imply  that  the  difference 


64 


A   SYSTEM   OF   PSYCHOLOGY 


between  R  and  G  is  equal  to  that  between  R  and  B, 
etc.,  for  these  differences  are  incommensurable. 
We  might,  indeed,  use  a  circle  in  place  of  a  triangle, 
locating  the  fundamental  colors  thereon  at  appro- 
priate points;  and  this  "color  circle"  is  frequently 
employed  in  preference  to  the  "color  triangle." 


Fig.  3. 


Fig.  4. 


Now,  we  may  wish  to  represent  different  inten- 
sities of  color;  this  we  may  do  in  the  dimension  at 
right  angles  to  the  plane  of  the  "  color  triangle."  If 
we  wish  to  represent  another  complete  series  of  hues 
at  an  intensity  uniformly  higher  than  those  just  sup- 
posed to  be  represented  by  the  triangle,  we  do  it  by 
a  second  triangle  above  and  parallel  to  the  first, 
as  in  fig.  3.  In  this  connection  we  find  the  peculiar 
fact  that  if  we  start  with  that  intensity  of  a  pure 
spectral  light  which  gives  the  maximal  saturation, 
and  steadily  increase  the  intensity,  the  saturation  of 
the  sensation  soon  begins  to  decrease,  and  at  a  cer- 


SENSATION   QUALITY  65 

tain  high  intensity  of  the  stimulus  the  color  becomes 
white.  Schematically,  this  would  mean  that  the 
triangles  must  be  drawn  smaller  and  smaller,  as  we 
go  up,  until  they  become  points.  In  decreasing  the 
intensity  the  same  phenomenon  is  met;  all  colors 
becoming  gray  (red  is  possibly  an  exception)  before 
being  extinguished;  the  saturation-decrease  being 
more  sudden  at  this  end. 

The  qualitative  changes  perceived  as  a  light  stimu- 
lus of  practically  homogeneous  wave  length  is  pro- 
gressively increased  from  zero  to  a  maximum,  are 
shown  schematically  in  fig.  4.  The  line  w  p  z  is  the 
series  of  grays,  or  neutral  sensations,  and  is,  there- 
fore, conceived  as  perpendicular  to  the  color  tri- 
angle (or  color  circle)  at  the  centre. 

The  interval  z  k,  in  which  the  stimulus  arouses 
only  the  sensation  of  gray;  the  interval,  therefore, 
between  the  light-threshold  and  the  color-threshold, 
is  called  the  photochromatic  interval.  Logically, 
there  is  an  upper  photochromatic  interval  also,  but 
it  is  not  susceptible  of  measurement  because  of  the 
incident  damage  to  the  eye. 

Since  the  rate  and  the  magnitude  of  change  are 
represented  here  purely  schematically,  we  may  rep- 
resent any  hue  by  a  curve  of  the  same  form.  Rang- 
ing them  all   around    the   common   gray-axis,   we 


66  A    SYSTEM   OF   PSYCHOLOGY 

derive  (i.  e.,  by  rotating  fig.  4  on  the  axis  w  p  z)  an 
onion-like  figure,  which,  taken  as  a  solid,  contains 
schematically  all  possible  visual  sensations.1  Linear 
distance  parallel  with  the  axis  represents  intensity- 
change;  linear  distance  perpendicular  to  the  axis 
represents  saturation  change;  and  angular  distance 
about  the  axis  represents  change  of  hue. 

Since  white  (gray)  is  equivalent  to  a  certain  pro- 
portion of  red,  green,  and  blue,  it  is  evident  from 
the  color  triangle  that,  for  any  color,  we  can  find 
another  color  which  when  mixed  with  it  will  pro- 
duce gray,  provided  the  intensities  of  the  two  are 
properly  chosen;  for  all  points  on  the  triangle  (ex- 
cept the  vertices)  represent  combinations  of  two  of 
the  fundamental  colors:  and  to  any  combination  of 
two  it  is  possible  to  add  one  of  them  and  the  third  in 
such  proportions  that  the  proportions  of  the  three 
shall  be  whatever  is  desired.  And  practically  the 
conditions  are  quite  easy  of  fulfilment.  Colors 
which  combine  thus  in  pairs  to  produce  gray  are 
called  complementary.  Examples  of  complement- 
ary colors  are:    red  and  a  certain  blue-green;    or- 

1  This  is  the  tri-dimensional  figure  on  the  basis  of  the  color 
circle.  It  might  be  constructed  on  the  basis  of  the  triangle, 
only  the  description  of  the  generation  is  a  little  more  difficult. 
( lommonly,  the  line  z  m  w,  of  fig.  4,  is  made  a  semicircle  or  else 
two  straight  lines,  from  m  to  w  and  m  to  z.  The  solid  figures 
become  then  a  sphere  or  a  double  pyramid  or  a  double  cone. 


SENSATION   QUALITY  67 

ange  and  greenish-blue:    yellow  and  indigo-blue; 
green  and  reddish-purple. 

We  have  used  the  terms  white  and  gray  inter- 
changeably. White  is  a  relative  term  denoting  the 
brightest  gray.  Any  piece  of  paper  which  looks 
"white"  may,  if  placed  on  a  still  whiter  one  be 
made  to  be  a  dull  gray;  and  the  new  "white"  may 
be  literally  put  in  the  shade  by  a  still  brighter. 
"Black,"  too,  is  purely  relative.  The  blackest 
paper  obtainable  looks  dark  gray  against  a  black 
velvet.  Black  and  white  are  contents  of  conscious- 
ness, but  not  sensations  simply;  they  are  complex 
sensations  of  gray  perceived  in  certain  relations. 
The  difference  between  the  various  neutral  grays 
is  one  of  brightness  only,  that  is,  they  form  an  in- 
tensive series  of  identical  quality  (whether  we  con- 
sider it  a  simple  quality,  or  a  mixture  of  three). 

7.  Achromopsia  and  Parachromopsia 

Individuals  differ  in  the  sensitiveness  of  their 
color  processes  to  the  action  of  light  of  various  wave 
lengths,  and  in  the  cases  of  some  persons  the  varia- 
tion from  the  normal  is  so  considerable  that  these 
persons  are  called  color-blind.  In  extreme  cases  the 
patient  can  see  no  color  at  all,  everything  appearing 
to  him  gray;   so  that  the  landscape  which  shows 


68  A    SYSTEM   OF   PSYCHOLOGY 

to  us  a  wealth  of  hues  presents  itself  to  him  as  a 
black  and  white  sketch.  Yet  the  color-blind  man 
may  not  realize  that  his  vision  is  different  from  yours, 
and  if  you  ask  him  the  color  of  the  grass  he  will  say 
"green,"  for  he  has  always  heard  it  called  so,  and 
has  no  way  of  knowing  that  "green"  does  not  mean 
to  you  the  same  particular  shade  of  gray  it  does  for 
him.  Such  a  person  is  said  to  be  totally  color-blind, 
or  achromopsic. 

More  numerous  than  the  "achromopes"  are  per- 
sons who  see  colors,  but  not  as  we  see  them;  they 
are  called  partially  color-blind,  or  par  acliromopsic; 
par  achromopes.  The  eommonest  case  is  that  in 
which  only  blue  and  yellow  are  seen  (in  addition  to 
gray),  the  normal  red  and  green  of  the  spectrum 
appearing  yellow  and  a  certain  part  of  the  blue-green 
appearing  gray,  as  does  also  a  certain  purple  (not 
in  the  spectrum,  of  course,  but  mixed  from  blue  and 
red),  which  is  to  the  normal  eye  complimentary  to 
this  blue-green.  This  is  a  typical  sort  of  dichro- 
mopsia  (two-color  vision).  Other  persons  see  some 
green  in  addition  to  the  gray,  yellow,  and  blue; 
others  probably  see  gray,  red,  and  one  other  color; 
and  still  others  see  only  gray  and  one  color,  which 
is  probably  green  in  some  cases. 

How  large  the  list  of  color  abnormalities  in  vision 


SENSATION    QUALITY  G9 

jtarachromopsias — may  be,  we  cannot  even  guess, 
as  yet,  but  enough  is  known  to  assure  us  that  it  is 
not  small.  The  detection  of  these  abnormalities  is 
of  great  importance  for  railroad  and  nautical  pur- 
poses, but  is  difficult,  and  possible  only  by  skilfully 
arranged  tests.  Exact  work  can  be  done  with  spec- 
tral light  and  elaborate  apparatus,  but  rough  tests 
can  be  made  with  colored  worsteds  or  silks.  A  few 
cases  have  been  found  in  which  the  patient  had  one 
eye  achromopsic,  or  parachromopsic,  and  the  other 
normal,  or  nearly  so,  so  that  he  could  tell  just  what 
colors  were  seen  with  the  defective  eye;  and  these 
cases  have  given  indispensible  assistance  in  diag- 
nosing the  color  defects  of  others. 

We  must  distinguish  between  true  parachromop- 
sia  and  mere  lack  of  memory  for  hues,  or  inability 
to  name  them  properly,  or  awkwardness  in  sorting 
them.  While  it  is  true  that  a  genuine  defect  may 
escape  detection  sometimes,  it  is  also  true  that  a. 
person  may  fail  miserably  in  a  color  test,  and  yet  be 
chromopsically  normal,  just  as  a  nervous  patient 
may,  by  confused  reports  on  the  oculist's  tests,  be 
convicted  of  serious  astigmatism,  and  yet  not  be 
astigmatic  at  all.  It  is  said  that  there  are  more 
color-defective  men  than  women,  but  this  may  be 
doubted.     Women  are  much  more  apt  to  escape 


70 


A    SYSTEM   OF   PSYCHOLOGY 


detection,  even  by  themselves,  because  of  more  prac- 
tice in  handling  colors. 

The  totally  color-blind  person  is  apt  to  be  able  to 
see  in  a  dim  light  better  than  a  normal  person,  and 


to  find  unbearable  a  light  which  is  for  the  normal 
person  reasonably  strong.  This  suggests  at  once 
the  possibility  that  all  three  color-processes  are 
present  in  his  eye,  and  that  they  are  alike  excitable 
by  rays  of  light  of  any  wave  length  included  in  the 
spectrum.     This  hypothesis  is  also  necessitated  by 


SENSATION    QUALITY 


71 


the  fact  that  in  cases  of  monocular  achromopsia 
gray  is  seen  alike  by  both  eyes.  This  condition  is 
represented  by  the  curves  in  fig.  8,  where  the  achro- 


Fig.  7. 


Fig.  8. 


mopsia  is  nearly  complete;  if  complete  the  three 
curves  would  exactly  coincide  throughout.  Fig.  5 
gives  the  probable  relations  of  excitability  of  the 
three  processes  in  the  normal  eye,  showing  how 
each  color  is  excited  by  practically  all  rays  of  the 


72  A    SYSTEM   OF   PSYCHOLOGY 

spectrum,  but  principally  in  a  certain  range.  In 
these  and  the  following  curves  the  horizontal  axis 
represents  the  spectrum,  and  the  ordinate  at  any 
point  represents  the  relative  degree  of  excitation  of 
the  process  by  the  light  from  that  point  in  the  spec- 
trum. The  curves  are  not  intended  to  represent 
any  specific  ratios,  only  the  general  positions  being 
in  point.  Exact  forms  for  the  curves  have  been  com- 
puted by  several  theorizers,  but  such  computations 
are,  after  all,  of  little  value,  since  they  represent  the 
carrying  out  of  the  results  of  certain  postulates. 

Curves  I,  II,  and  III,  in  fig.  5,  show  the  probable 
relative  excitability  of  the  red,  green  and  blue  proc- 
esses respectively,  for  the  normal  eye.  Curve  IV 
represents  the  relative  brightness  of  the  different 
parts  of  the  spectrum  as  determined  by  the  flicker 
method.  Curves  I,  II,  and  III  are  so  drawn  that 
the  sum  of  their  ordinates  at  any  point  on  the  spec- 
trum (X-axis)  is  equal  to  the  ordinate  of  curve 
IV  at  that  point. 

Curves  I,  II,  and  III  in  figs.  6,  7,  and  8  are  ar- 
bitrarily modified  from  the  curves  in  fig.  5,  so  that 
they  may  represent  the  color-vision  abnormalities 
described.  Curve  IV  in  these  figures  is,  accordingly, 
derived  by  summing  the  ordinates  of  curves  I,  II, 
and  III. 


SENSATION   QUALITY  73 

Fig.  (i  shows  the  probable  excitability  of  one  type 
of  yellow-blue  parachromopsia  (red-green  blind- 
ness), in  which  the  spectrum  is  of  practically  normal 
length.  This  was  formerly  supposed  to  be  "green- 
blindness"  and  is  often  designated  by  the  term 
"proteranopia."  Fig.  7  represents  the  excitability 
in  another  type  of  yellow-blue  parachromopsia, 
where  the  spectrum  is  shortened;  formerly  called 
"red-blindness";  "deuteranopia."  There  are  all 
sorts  of  parachromopsias  intermediate  between  these 
two,  constituting,  as  we  said  before,  the  more  numer- 
ous sorts  of  color-blindnesses.  Other  abnormalities 
than  "yellow-blue"  vision  are  known  to  exist,  and 
may  be  represented  by  proper  modification  of  the 
curves.1 

The  normal  eye  is  not  equally  sensitive  to  light 

1  The  tri-chrome  theory  must  not  be  understood  as  an 
explanation  of  the  facts  of  "color-blindness,"  or  of  the  other 
complex  phenomena  of  color  vision.  It  is  merely  a  compre- 
hensive statement  of  all  the  facts;  a  descriptive  theory,  in 
short.  It  is  not  the  only  possible  statement,  but  has  the  vir- 
tue of  being  the  simplest.  We  can,  for  example  (contrary, 
it  is  true,  to  general  opinion),  give  just  as  thorough  a  state- 
ment with  red,  yellow,  and  blue  as  the  fundamental  colors, 
and  work  it  out  logically  to  cover  all  the  known  facts;  but 
it  would  be  more  complicated.  A  slightly  less  complicated 
theory  than  this  might  be  constructed  with  four  fundamental 
processes  and  colors — it  is  all  a  matter  of  drawing  the  curves 
for  the  normal  spectrum.  Still  other  possibilities  are  open, 
but  for  the  present  it  seems  best  to  rest  on  the  simplest  state- 
ment. 


74  A    SYSTEM   OF   PSYCHOLOGY 

and  color  in  all  parts.  At  the  centre  of  the  retina 
colors  are  discriminated  with  the  greatest  ease,  but 
as  you  go  out  toward  the  edge  of  the  visual  field 
discrimination  becomes  more  difficult,  and  the  col- 
ors lose  in  saturation  until  at  the  extreme  limit  of 
visibility  they  are  practically  all  gray.  It  is  some- 
times said  that  the  margin  of  the  retina  is  totally 
color-blind,  and  the  zone  intermediate  between  the 
margin  and  a  certain  central  area,  red-green  blind. 
This  is  only  partly  true.  The  angular  distance 
from  the  centre  to  which  any  color  can  be  carried, 
and  yet  be  visible  in  its  proper  hue,  depends  on 
practice,  intensity,  area, and  duration.  With  intense 
spectral  light,  lasting  but  an  instant,  the  colors  can, 
after  considerable  practice,  be  discriminated  nearly 
to  the  periphery. 

8.  Color  Adaption  and  Contrast 

Protective  adaptation  is  especially  noticeable  in 
the  visual  realm,  but  takes  several  forms.  In  addi- 
tion to  the  control  of  the  stimulus  by  the  iris  and 
of  the  sensitivity  of  the  nerve-endings  by  the  retinal 
pigment,  there  are  adaptive  changes  which  go  on 
either  in  the  retina  or  in  the  brain,  by  virtue  of 
which  any  stimulus  tends  to  produce  a  sensation 
which  becomes  more  and  more  gray  as  the  stimu- 


SENSATION   QUALITY  75 

lation  continues.  The  most  familiar  example  of 
this  phenomenon  is  found  in  yellow  lamplight, 
which  soon  loses  its  yellowness  if  we  are  under  its 
illumination  exclusively.  The  change  is  also  rapid 
in  lights  which  are  yellow-green,  bluish-green,  or 
purple;  blue  changes  less  rapidly,  and  red  very 
slowly.  The  change  is  not  essentially  connected 
with  loss  of  total  intensity,  and  so  is  not  to  be  con- 
fused with  fatigue. 

In  terms  of  the  tri-chrome  theory,  color  adapta- 
tion is  a  decrease  in  sensitiveness  of  processes 
strongly  stimulated,  with  increase  in  sensitiveness  of 
processes  feebly  stimulated.  If,  for  instance,  blue- 
green  light  is  cast  on  the  retina,  the  blue  process  and 
the  green  process  are  strongly  excited,  the  red  proc- 
ess hardly  at  all;  the  result  is  a  sensation  com- 
plex in  which  blue  and  green  predominate.  As 
the  light  continues  to  act,  the  blue  and  the  green 
processes  respond  progressively  less  and  less, 
and  the  red  process  more  and  more,  so  that  the 
sensation  complex  becomes  less  and  less  satu- 
rated. 

The  results  of  these  adaptative  changes  are  clearly 
shown  when  colorless  (gray)  light,  e.  g.,  from  a  gray 
wall  or  paper  in  ordinary  daylight,  is  allowed  to  fall 
on  the  part  of  the  retina  previously  stimulated  by 


76  A    SYSTEM   OF   PSYCHOLOGY 

the  colored  light.  Under  these  conditions  the  proc- 
ess or  processes  that  have  increased  in  sensitivity 
respond  more  intensely  than  the  process  or  proc- 
esses that  have  decreased,  and  the  result  is  a  tinge 
of  the  color  complementary  to  the  original  color. 
This  color  effect  occupies  the  exact  retinal  area 
occupied  by  the  exciting  color,  and  its  appearance 
is  known  as  the  negative  after-image.1 

The  quality  of  a  light  is  determined,  in  the  case 
just  mentioned,  by  the  intensive  relations  of  the 
physio-psychological  color  components.  In  all  cases 
the  hue  of  the  sensation  roused  by  any  given  stim- 
ulus is  a  variable  affair,  depending  on  the  condi- 
tion of  the  portion  of  the  retina  on  which  the  stim- 
ulus falls,  and  on  the  condition  of  the  adjacent 
retinal  areas.  The  latter  factor  determines  what  is 
known  as  enlor  contrast,  or,  to  distinguish  it  surely 
from  the  after-image  effect,  .simultaneous  contrast. 
If  you  look  at  a  small  gray  card  placed  on  a  large 
colored  surface,  you  get  the  contrast  effect  very 
clearly:  the  card  will  appear  tinged  with  the  color 
complementary   to  that  of  the  background.     The 


1  Adaptation  may  take  place,  and  be  followed  by  the 
characteristic  negative  after-image,  without  any  sensation  of 
color  during  adaptation  being  noticed.  This  may  be  demon- 
strated by  placing  the  subject  in  colorless  light,  to  which 
minute  amounts  of  a  color  are  continuously  added. 


SENSATION   QUALITY  77 

eyes  must  not  move  during  this  observation,  but 
must  remain  steadily  fixed,  or  after-images  will 
occur,  and  counterfeit  the  effect;  slight  movements 
will  unavoidably  occur,  giving  rise  to  narrow  after- 
image effects  along  the  edges  of  the  card;  so-called 
cdge-contrad.  The  saturation  of  the  contrast-color 
may  be  increased  by  covering  the  card  and  back- 
ground with  a  piece  of  tissue-paper  or  ground  glass; 
by  squinting  through  the  nearly  closed  lids;  or  by 
darkening  the  room  (as  by  pulling  down  the  win- 
dow-shades). No  matter  what  the  brightness  and 
saturation  of  the  colored  background,  or  the  bright- 
ness of  the  gray,  one  of  these  changes  will  heighten 
the  contrast-color. 

No  satisfactory  explanation  of  the  contrast  effect 
has  as  yet  been  found,  but  the  most  plausible  theory 
is  that  substances  essential  to  the  processes  in  the 
retinal  area  stimulated  by  the  colored  rays  are 
drawn  from  the  area  stimulated  by  the  gray,  leav- 
ing that  area,  therefore,  more  sensitive  to  the  other 
rays  of  the  spectrum,  because  relatively  better  sup- 
plied with  substances  reacting  to  those  rays.  Of 
course  the  basis  for  this  phenomenon,  as  well  as  for 
that  of  after-images,  may  not  be  in  the  retina,  but 
may  be  in  the  brain;  there  is  absolutely  no  means 
of  deciding  at  present  between  the  two  possibilities, 


78  A   SYSTEM   OF   PSYCHOLOGY 

but  the  fashion  is  to  suppose  that  the  retinal  hy- 
pothesis is  the  true  one. 

An  interesting  experiment  which  possibly  demon- 
strates the  transfer  of  photochemical  substance 
across  the  retina,  may  be  performed  with  an  "  Archi- 
medean spiral,"  in  black  and  white,  on  a  pasteboard 
disk;  this  is  supplied  in  the  Munsterberg  set  of  il- 
lusions (by  the  Milton  Bradley  Co.).  If  the  disk 
is  rotated  steadily — a  clock-work  or  electric  motor 
with  controllable  speed  is  best,  but  a  hand-power 
color-mixer  will  do — at  such  a  rate  that  when  the 
eyes  are  fixed  on  the  centre,  rings  run  outward, 
like  those  from  a  stone  dropped  in  the  water;  if 
these  rings  are  observed  several  seconds  (the  eyes 
not  moving),  and  if  the  eyes  are  then  quickly  closed 
and  covered  with  a  large  piece  of  black  cloth, 
"retinal  streaming"  will  be  observed,  the  bright 
streamers  running  from  edge  to  centre  of  the  dark 
field.  If  the  disk  is  rotated  in  the  opposite  direc- 
tion, so  that  the  rings  run  toward  the  centre,  the 
streaming  will  be  from  the  centre  out.  The  closing 
and  covering  of  the  eyes  must  be  very  quickly  done; 
the  cloth  being  held  on  the  palms  of  the  outspread 
hands  ready  for  action  while  observing  the  rings. 
After  some  practice  the  streaming  can  be  observed 
by  simply  closing  the  eyes,  without  covering.     A 


SENSATION   QUALITY  79 

more  striking  method  is  to  have  a  single  source  of 
light,  which  illuminates  the  disk  brightly,  and  to 
cut  this  light  off  at  the  proper  moment,  leaving  the 
room  in  total  darkness.  Turning  out  an  electric 
light  will  not  do,  as  the  light  dies  too  slowly. 

The  streaming  may  be  observed  on  the  disk  itself 
while  it  is  in  rotation;  it  is  in  the  direction  of  move- 
ment of  the  rings,  and  gives  them  a  peculiar  wavy 
appearance.  On  looking  suddenly  at  some  other 
object,  the  streaming  in  the  reverse  direction  makes 
the  object  seem  to  expand  or  shrivel  up  in  an  odd 
way. 

If  we  assume  a  definite  "color  substance"  in  the 
retina  corresponding  to  each  of  the  three  hypotheti- 
cal color  processes,  then  it  is  a  natural  step  to  as- 
sume that  these  substances  are  attracted  to  the  re- 
gion stimulated  by  the  white  rings,  and  so  drawn 
outward  (or  inward)  with  the  rings.  This  is  ren- 
dered still  more  probable  by  the  occurrence  of  what 
are  known  as  "Fechner's  colors";  as  you  look  at 
the  disk,  it  will  sometimes  take  on  a  red  or  green 
cast;  other  colors  occur  seldom.  This  can  be  ex- 
plained by  stronger  attraction  for  one  of  the  sub- 
stances, when  the  rate  of  rotation  of  the  disk  is  such 
that  following  rings  coincide  with  the  greatest  con- 
centrations of  one  of  the  substances. 


80  A   SYSTEM   OF   PSYCHOLOGY 

9.  Auditory  Sensations 

The  nerve  endings  of  the  acoustical  apparatus 
are  in  the  cochlea  of  the  ear,1  and  the  cortical  cen- 
tre is  in  the  superior  temporal  convolution.2  The 
acoustical  stimulus  is  a  vibratory  movement  of  the 
air,3  which  is  communicated  through  the  external 
auditory  meatus  to  the  middle  ear  (tympanum),  and 
thence  through  two  windows  (fenestra  ovalis  and 
fenestra  rotunda)  in  the  bony  wall  to  the  vestibule 
and  cochlea.  It  was  formerly  supposed  that  the 
little  bones  (ossicles)  transmitted  the  vibration  from 
the  tympanic  membrane  to  the  oval  window  into 
which  the  head  of  the  stirrup  bone  is  fitted,  it  being 
thought  to  act  like  a  piston;  but  the  discovery  of 
individuals  whose  ossicles  have  been  destroyed,  and 
who  hear  nearly  as  well  as  normal  persons  has 
ruined  this  theory.  It  is  probable  that  the  air  of 
the  tympanum  conducts  the  sound,  and  the  bones 
act  as  a  damper.     Vibrations  may  be  carried  to  the 


'  Piersol,  figs.  1242,  1247,  1248,  1251,  1252,  1255,  1256, 
1257,  1259,  1260,  1264,  1268,  1271,  1272,  1273;  Quain,  III, 
pt.  Ill,  figs.  78,  87,  102,  108,  111,  113,  129,  131,  135,  136. 

-'Piersol,  figs.  1042,  1043,  1071;  Howell,  figs.  93,  94; 
Schiifer,  fig.  351. 

1  Hnllock  (Duff),  pp.  301-307;  Zahm,  pp.  21-53;  M'Ken- 
drick  and  Gray  (Schiifer),  pp.  1149-1168;  Howell,  pp.  371- 
375. 


SENSATION   QUALITY  81 

middle  ear  through  the  bones  of  the  skull,  and  so 
reach  the  inner  ear.  You  may  test  this  by  touch- 
ing the  head  to  any  object  emitting  feeble  vibrations, 
as  a  tuning-fork,  violin,  or  piano,  faintly  sounding. 

The  exact  manner  in  which  the  direct  excitation 
of  the  auditory  nerve  endings  (hair-cells  on  the 
basilar  membrane)  occurs  has  been  the  subject  of 
much  speculation.  The  Helmholtz  "piano-string" 
theory  was  formerly  held  to  be  a  satisfactory  expla- 
nation, and,  indeed,  it  is  in  accord  with  many  of  the 
psychological  and  pathological  facts  of  audition; 
but,  nevertheless,  the  anatomical  details  of  the  coch- 
lea are  now  believed  to  be  against  that  hypothesis. 
Helmholtz  supposed  elements  in  the  basilar  mem- 
brane free  to  vibrate  selectively  to  the  rates  of  move- 
ment to  which  they  were  adapted,  and  by  their 
vibration  to  excite  the  contiguous  hair  cells.  The 
vibration  rates  to  which  these  elements  were  sup- 
posed to  be  "tuned"  increased  progressively  from 
the  apex  of  the  cochlea  to  the  "lower"  end  of  the 
membrane;  thus  the  series  of  perceptible  pitches 
corresponded  to  the  series  of  hair  cells  and  vibra- 
tory elements  functionally  connected  with  them.1 

The  latest  investigations  point  to  the  excitation  of 

1  For  details  on   the  Helmholtz  Theory,  see  Howell,  pp. 
376-379;    M'Kendrick  (Schiifer),  pp.  1171-1185. 


82  A    SYSTEM   OF   PSYCHOLOGY 

the  hair  cells  by  the  movements  of  the  tectorial 
membrane:  Beyond  this,  we  are  still  in  the  realm 
of  speculation.  A  number  of  theories  have  been 
elaborated  in  addition  to  that  of  Helmholtz,  and 
two  of  them  seem  to  be  worthy  of  entertainment. 
These  we  may  call  briefly  the  telephone  theory, 
and  the  extensity  theory. 

The  telephone  theory  antedates  Helmholtz's, 
but  has  been  recently  revived  in  modified  forms. 
Briefly,  it  holds  that  pitch  is  conditioned  solely  by 
the  frequency  of  the  nervous  impulses  transmitted 
to  the  brain — the  pitch -characteristic  being  thus 
supposed  to  be  a  product  of  the  brain  cells.  Now, 
whatever  the  exact  mechanism  for  transforming  the 
vibratory  impulses  transmitted  to  the  inner  ear  into 
hair-cell  stimulations,  the  apparatus  highly  sensi- 
tive to  one  rate  will  not  be  so  sensitive  to  other  rates. 
Hence  the  need  for  a  series  of  such  apparatus  (which 
is  furnished  in  the  cochlear  structures)  that  will 
give  the  maximal  sensitivity  to  a  great  range  of 
vibration  rates.  This  is  mechanically  the  most 
rational  of  all  the  theories;  it  also  has  the  advan- 
tage of  explaining  the  pathological  phenomena,  and 
many  other  details,  on  practically  the  same  simple 
grounds  as  does  the  Helmholtz  theory,  while  not 
open  to  the  objections  to  the  latter. 


SENSATION    QUALITY  83 

The  extensity  theory  is  less  happy  mechanically, 
but  more  strictly  in  accord  with  the  psychological 
facts.  Moreover,  it  does  not  turn  the  whole  matter 
of  pitch  over  to  unidentified  brain  activity,  but  puts 
it  on  a  basis  where  auditory  sensation  is  strictly 
comparable  with  other  sensations.  This  theory 
holds  that  the  frequency  of  the  vibration  deter- 
mines the  length  of  the  series  of  hair  cells  (measured 
from  the  vestibular  end  of  the  total  series)  stimu- 
lated by  a  given  tone.  The  slower  the  vibration, 
the  more  cells  stimulated.  Below  a  certain  rate, 
all  the  nerve  endings  are  stimulated;  above  a  cer- 
tain rate,  none. 

So  far  as  we  can  discover  there  is  but  one  ele- 
mentary auditory  quality.  It  is  customary  to  speak 
of  pitch  as  quality,  but  that  is  an  unjustifiable  use 
of  the  word,  for  the  difference  between  red  and 
blue  is  not  at  all  of  the  same  sort  as  the  difference 
between  a  low  and  a  high  note,  although  physically 
they  both  correspond  to  a  difference  of  vibration 
rate. 

It  is  true  that  as  notes  are  sounded  they  differ  in 
a  respect  other  than  pitch,  which  again  is  com- 
monly called  quality.  The  note  of  the  violin,  when 
of  the  same  pitch  as  the  note  of  the  flute,  is  readily 
distinguishable  from  it.     Low  and  high  notes  of  the 


84  A    SYSTEM   OF   PSYCHOLOGY 

same  instrument  differ  more  or  less  in  the  same 
way.  This  difference  is  one  of  complexity  and 
intensity  of  components,  and  in  strict  discourse 
should  not  be  called  qualitative.  The  best  word 
available  for  this  quasi-character  of  tones  is  timbre. 
The  Helmholtz  theory  of  audition  makes  pitch 
analogous  to  local  sign  of  touch  and  sight.  The 
"telephone  theory"  might  assign  a  strictly  quali- 
tative nature  to  pitch,  although  acceptance  of  the 
theory  does  not  necessarily  commit  one  to  the 
qualitative  view.  On  purely  psychological  grounds, 
pitch  is  analogous  to  extensity  of  visual  and  tactual 
sensation  and  we  shall,  therefore,  treat  it  further 
under  the  head  of  extensity. 

10.  Cutaneous  and  Subcutaneous  Sensations 

Scattered  through  the  skin,  and  the  tissues  im- 
mediately beneath  it,  the  mucus  membrane,  the 
peritoneum  of  the  abdominal  cavity,  the  tissues 
adjacent  to  the  apposed  joint-surfaces,  and  in  the 
muscles,  tendons,  and  bones  themselves,  there  are 
numerous  sensory  nerve  endings,  of  a  wide  range 
of  complexity,  which  respond  to  mechanical  stim- 
ulation and  to  temperature  changes.  The  joint, 
muscle,  and  tendon  endings  we  will  discuss  in  the 
next   section,  treating  here  only  those  in  and    im- 


SENSATION   QUALITY  85 

mediately   beneath    the    superficial   coverings   and 

linings. 

The  simplest  of  these  organs  are  no  more  than 
slight  knobs  on  the  ends  of  nerve  fibres,  in  contact 
with  cells  of  the  tissues  in  which  they  are  placed. 
A  development  from  the  knob  is  a  little  disk,  or 
concave  plate,  in  contact  with  a  cell  as  the  cup  with 
an  acorn.  In  a  third  form,  the  nerve  ending  is  be- 
tween two  specialized  cells.  In  higher  forms  there 
are  several  knobs,  or  platelets,  on  branches  of  the 
nerve  fibre,  or  fibres,  which  are  enclosed  within 
special  cells  or  structures.  The  most  complicated 
organs  contain  networks  or  "skeins"  of  nerve  fibres 
of  great  intricacy  . 

As  these  different  sorts  of  nerve  endings  were  dis- 
covered they  were  given  the  names  of  their  dis- 
coverers. Thus  there  are  "end-bulbs  of  Krause," 
"Pacinian  corpuscles,"  "plume-organs  of  Ruffini" 
and  so  on.  As  more  types  are  discovered,  and  as 
they  are  found  to  form  a  series  in  increasing  com- 
plexity, these  names  become  of  less  importance 
except  to  the  anatomist.1 

The  cortical  centres  for  cutaneous  sensation  are 

■For  dermal  and  sub-dermal  structures  and  organs  see 
Piersol,  figs.  867  to  875,  and  1146  to  1148;  Quain,  figs.  389 
to  398,  402,  403,  407,  408. 


86  A    SYSTEM   OF   PSYCHOLOGY 

variously  located  by  different  physiologists.  The 
most  probable  theory  is  that  they  are  near  the 
"motor  zone,"  on  the  anterior  side  of  the  fissure  of 
Rolando.1  This  statement  holds  also  for  the  sim- 
ilar sensations  from  the  mucus  membrane,  and 
from  the  subcutaneous  tissues.  For  convenience, 
and  in  accordance  with  established  custom,  we  will 
refer  to  these  all  as  "cutaneous"  except  where  we 
make  specific  distinction. 

The  qualities  of  cutaneous  sensation  are  fairly  dis- 
tinct. Touch,  tickle,  warmth,  and  cold,  are  easily 
discriminated.  Pressure  is  possibly  of  a  different 
quality  from  touch.  Pain  is  commonly  considered 
as  a  specific  quality  of  sensation,  but  of  that  we  will 
speak  below. 

Touch  is  aroused  by  light  mechanical  stimulation 
of  the  skin  (or  of  the  mucus  membrane,  etc.).  It 
may  also  be  aroused  by  electrical  stimulation,  by 
radiant  heat,  or  (on  the  mucus  membrane)  by  the 
action  of  certain  substances  denoted  as  "astrin- 
gent." Tickle  is  aroused  by  a  lighter  stimulation, 
and  pre-eminently  if  the  stimulus  is  of  the  stroking 
sort.  It  is  practically  impossible  to  arouse  tickle 
without  in  some  degree  arousing  touch  also,  and 
light  touches  are  very  apt  to  give  gargalic  sensation 
1  Piersol,  figs.  1041-1043. 


SENSATION    QUALITY  87 

along  with  the  tactual;  nevertheless,  the  two  sen- 
sation-qualities  are  so  distinct  that  they  are  unmis- 
takably discriminated.  They  are  also  strongly 
distinguished  in  respect  to  intensity  of  stimulus  and 
motor  response.  A  very  light  stimulation  will 
arouse  a  powerful  tickle  sensation,  and  the  impulse 
to  move  the  hand  to  the  spot  tickled,  or  to  move  the 
tickled  member,  is  usually  irresistible.  The  develop- 
ment of  this  strong  reflex  through  the  necessity 
of  guarding  against  insects  has  often  been  conject- 
ured. If  the  stimulation  is  increased  in  intensity, 
the  sensation  of  touch  replaces  that  of  tickle,  and 
the  sensation  intensity  is  much  reduced,  as  is  also 
the  strength  of  the  reaction-impulse. 

The  production  of  tickle  sensation  usually  in- 
volves also  the  production  of  organic  processes  and 
sensations  in  addition  to  the  specific  reflex.  This 
general  bodily  disturbance,  which  doubtless  has  its 
function  in  the  acceleration  and  intensification  of 
the  reaction,  is  commonly  known  as  tickle,  or  tick- 
lishness;  but  this  we  are  not  discussing  here.  We 
are  referring  to  the  quality  of  the  superficial  sensa- 
tion alone. 

Pressure,  as  we  use  the  term  (usage  in  regard  to 
"touch"  and  "pressure"  varies  very  much)  is 
aroused  from  organs  deeper  than  the  skin;    or  at 


88  A    SYSTEM   OF   PSYCHOLOGY 

least  it  is  aroused  by  physical  pressure  heavier  than 
is  required  to  arouse  touch.  It  may  be  of  the 
same  quality,  nevertheless;  inspection  shows  in  it 
nothing  certainly  different  from  intense  tactual 
sensation  free  from  the  gargalic;  and  common  usage 
treats  touch  and  pressure  as  one. 

Warmth  and  cold  are  distinct  qualities,  although 
dependent  on  variations  in  the  same  physical  tem- 
perature continuum.  In  this  respect  they  are  perhaps 
analogous  to  touch  and  tickle.  The  conditions  for 
the  arousal  of  warmth  and  cold  are  complex,  and 
as  yet  not  well  understood.  When  the  skin  has 
been  maintained  at  a  certain  temperature  for  a 
short  time  it  usually  ceases  to  respond  to  that  ther- 
mic condition  with  either  rhigotic  or  thalpotic  sen- 
sation. This  temperature  is,  therefore,  called  the 
neutral  'point  for  that  portion  of  the  skin  at  that 
particular  time.  If  now  the  skin  is  subjected  to 
temperature  conditions  above  this  neutral  point,  the 
nerve  endings  are  so  stimulated  that  warmth  sen- 
sations occur;  conversely,  if  the  skin  is  subjected 
to  a  temperature  below  the  point  of  neutrality,  pro 
tempore,  cold  is  felt;  the  sensation  persisting  in 
either  case  until  a  new  neutral  point  is  established. 
There  are,  however,  cases  which  this  formulation 
docs  not  seem  to  fit,  and  a   formulation    in    terms 


SENSATION   QUALITY  89 

of  a  fcmpcraturc-zrro  has  been  attempted.  When 
the  temperature  of  the  skin  is  above  this  zero  (it  is 
supposed)  warmth  sensations  are  aroused;  when 
below,  cold.  This  theory  may  be  stated  adequately 
as  follows:  When  we  feel  cold  (or  warm)  the  tem- 
perature of  the  skin  is  below  (or  above)  a  temperature 
at  which- — under  conditions  otherwise  the  same — 
we  would  feel  neither  warmth  nor  cold.  This  may 
be  true,  but  it  doesn't  seem  to  help  much.1 

As  the  temperature  of  the  body  varies  in  differ- 
ent regions,  objects  which  feel  warm  to  one  part 

1  Perhaps  the  safest  hypothesis  is  that  the  nerve  endings 
adjust  themselves  to  a  rate  of  heat-radiation  from  the  skin, 
if  that  rate  lies  within  a  certain  range,  and  is  maintained  for 
a  certain  length  of  time,  so  that  they  are  not  stimulated.  If, 
now,  the  rate  is  suddenly  changed,  stimulation  of  the  appro- 
priate end-organs  takes  place  and  continues  until  the  organs 
adapt  themselves  to  the  new  rate.  If  the  change  is  made 
gradually  the  protective  adaptation  may  take  place  with 
very  little,  or  practically  no,  sensation  as  in  the  case  of  color 
adaptation.  Thus,  if  the  hand  is  placed  in  water  which  feels 
"neutral,"  and  held  still  while  the  temperature  of  the  water 
is  slowly  raised  or  lowered,  the  water  may  be  heated  or  cooled 
to  a  point  which  would  normally. feel  hot  or  cold  to  the  hand, 
yet  in  this  case  no  sensations  be  aroused.  I  have  seen  a  pa- 
tient's hand  which  was  kept  in  warm  water  for  several  hours 
for  the  treatment  of  an  abscess.  The  water  became  slowly 
hotter,  and  so  scalded  the  hand  that  the  skin  came  off  over  the 
whole  surface,  yet  the  patient  found  the  water  only  comfort- 
ably hot.  Frogs  have  been  frozen  stiff,  or  boiled  to  death, 
while  making  no  efforts  to  escape  or  giving  other  signs  of  dis- 
comfort; the  water  in  which  the  animal  was  placed  being 
changed  in  temperature  very  slowly.  It  is  true  that  these 
last  illustrations  bear  more  specifically  on  the  so-called  pain 
sense;   but  see  text. 


90  A   SYSTEM   OP   PSYCHOLOGY 

may  feel  cool  to  another.  The  cold  and  warmth 
processes  may  be  aroused  by  agents  other  than 
temperature  changes;  pepper,  for  instance,  arouses 
warmth.  Or,  if  these  "warm"  substances  do  not 
directly  excite  the  nerve  endings,  they  at  least  lower 
the  neutral  point. 

It  has  been  alleged  that  heat  is  a  combination  of 
the  warmth  and  cold  qualities,  and  certain  experi- 
ments seem  to  support  this  view.  The  significance 
of  the  experimental  results  is,  however,  a  matter  of 
doubt,  and  there  is  as  yet  no  sufficient  reason  for 
considering  "heat"  as  other  than  an  intense  and 
perhaps  "painful"  warmth  sensation.1 

Pain  is  often  listed  as  a  specific  quality  of  sensa- 
tion. This  usage  arises  in  part  from  considera- 
tion of  the  topographic  distribution  of  cutaneous 
sensation  (see  below)  and  in  part  from  imperfect 
analysis.  The  use  of  the  word  pain  in  this  connec- 
tion is  due  to  a  confusion  of  the  pricking  or  stinging 
quality  of  the  sensation  aroused  by  the  stick  of  a 
needle  with  the  powerful  unpleasantness  which  often 

1  The  impulse  to  the  interpretation  of  heat  as  warmth  plus 
cold  comes,' doubtless,  from  certain  analogies,  between  warmth 
and  red,  and  cold  and  green.  We  usually  term  the  reds 
"  warm  "  colors,  and  greens  "  cold."  If  heat  were  a  combina- 
tion, either  psychologically  or  physiologically,  of  warm  and 
cold,  it  would  be  analogous  to  yellow.  The  next  step  would 
be  to  analogize  touch  to  blue,  and  pain  to  white. 


SENSATION    QUALITY  91 

characterizes  such  sensations.  By  sticking  the  hand 
with  the  needle  carefully,  so  that  the  sensation  is 
not  unpleasant,  the  same  quality  can  be  aroused, 
and  then  seems  to  be  no  other  than  a  small,  intense 
heat  sensation,  chiefly  distinguished  from  a  true 
heat  sensation  by  not  being  accompanied  by  sensa- 
tions of  warmth  (less  intense  heat)  from  adjacent 
localities  and  by  being  smaller  than  the  heat  ex- 
tensity.  By  these  differences,  and  possibly  by  dif- 
ferences in  the  time  relations — the  rapidity  of  de- 
velopment and  fading  of  sensations — we  are  usually 
able  to  distinguish  the  sensation  from  a  heat  stim- 
ulus from  that  of  a  sticking  or  cutting  stimulus. 
Sometimes,  however,  we  are  misled  and  may  feel 
a  prick  as  a  burn,  or  vice  versa. 

Itch  is  usually  a  combination  of  tickle  with 
warmth  or  heat.  Often  the  warmth  has  scattered 
points  of  relatively  high  intensity — prickling — which 
makes  the  itch  highly  unpleasant.  Rubbing  the 
itching  areas  relieves  the  situation  by  temporarily 
annulling  the  tickle. 

Ache,  such  as  may  be  aroused  by  plunging  the 
hands  in  ice- water,  is  not  a  cutaneous  sensation,  and 
is  capable  of  being  aroused  generally  throughout  the 
organism.  We  shall  speak  of  it  under  organic  sen- 
sation. 


92  A    SYSTEM   OF   PSYCHOLOGY 

Not  all  of  the  dermal  sensations  are  to  be  aroused 
readily  from  any  point  of  the  skin.  If  you  move  a 
cool  or  warm  metal  stylus  lightly  and  carefully  over 
the  skin,  you  will  find  that  only  at  certain  points  is 
the  thalpotic  or  rhigotic  sensation  produced,  unless 
between  these  points  the  stylus  is  allowed  to  rest 
long  enough  for  heat  to  be  transmitted  laterally. 
You  may  mark  these  points  where  the  sensation 
appears  directly  with  small  ink  spots  (one  color  for 
the  spot  stimulated  by  the  warm  stylus  and  another 
for  that  stimulated  by  the  cold) ;  then  you  may  test 
for  "pressure  points"  with  a  thin  bristle,  and  "pain 
points"  with  a  fine  needle.  You  will  find  that  many 
points  in  the  skin  may  be  penetrated  painlessly,  and 
on  many  the  pressure  of  the  bristle  will  not  be  felt, 
if  the  bristle  is  not  too  stiff.  You  make  a  chart  on 
the  skin  of  the  points  which  are  sensitive,  and  if  the 
marks  are  made  with  indelible  ink  you  may  find 
that  on  following  days  the  same  points  will  respond, 
and  the  ones  which  did  not  respond  continue  in- 
sensitive, if  the  degree  of  stimulation  is  the  same. 

A  great  deal  has  been  made  of  this  topographical 
distribution  of  sensation,  since  it  was  discovered, 
thirty  years  ago.  It  was  at  first  supposed  that  the 
points  indicated  the  locations  of  specific  end-or- 
gans, and  pieces  of  skin  have  been  cut  out  and  sub- 


SENSATION   QUALITY  93 

jected  to  microscopic  examination  in  the  hopes  of 
determining  these  organs,  but  without  success.  The 
permanence  of  the  sensory  points  has  been  doubted 
by  many  investigators  from  the  first,  and  it  has  at 
last  been  pretty  well  established  that  we  have  not 
to  do  with  points,  but  with  large  areas,  and  that  the 
points  of  maximal  sensitivity  within  these  areas 
vary  considerably  from  day  to  day.  The  error  of 
the  earlier  investigators  was  in  marking  the  points 
on  the  skin,  thus  prejudicing  their  succeeding  tests 
on  the  same  areas. 

The  latest  physiological  investigations  indicate 
that  there  are  three  sorts  of  cutaneous  and  subcu- 
taneous sensibility  from  the  physiological  point  of 
view.  These  are:  (1)  Deep  sensibility  to  heavy 
pressure  and  to  movement  of  the  tissues,  as  when 
a  member  is  flexed.  (2)  Protopathic  sensibility, 
"pain,"  heat,  and  cold;  heat  stimulated  by  temper- 
atures above  45°  C.  and  cold  by  temperatures  be- 
low 20°  C.  (assuming  the  neutral  point  to  be  about 
37°).  (3)  Epicritic  sensibility,  touch  and  tickle  and 
warmth  and  coolness;  warmth  and  coolness  pro- 
duced by  temperatures  lying  between  the  neutral 
point  and  45°  and  20°  respectively.  If  certain  sen- 
sory nerves  are  severed,  areas  supplied  by  them 
lose  sensations  of  the  second  kind,  but  the  first  and 


94  A    SYSTEM   OF   PSYCHOLOGY 

third  are  unaffected.  Severance  of  certain  other 
nerves  destroys  sensitiveness  of  the  third  sort,  with- 
out affecting  the  first  and  second.  And,  finally, 
severance  of  certain  "motor"  nerves  destroys  sensi- 
tiveness of  the  first  sort  only. 

These  facts  indicate  that  there  are  two  sets  of 
nerve  endings  giving  warmth  and  cold  sensations, 
but  under  different  conditions — the  one  set  respond- 
ing to  slight  stimulations,  and  capable  of  only  a 
feeble  action,  the  other  set  requiring  a  much  greater 
stimulus,  but  capable  of  intense  response.  These 
last-mentioned  organs  may  also  be  excited  by  me- 
chanical stimulations,  as  pressure  or  cutting.  There 
are  perhaps  eight  types  of  nerve  endings,  according 
to  their  functions,  as  follows:  tickle,  touch,  weak 
warmth,  weak  cold,  heat  and  "sharp  pain,"  cold 
(strong),  deep  pressure,  and  "dull  pain"  or  ache. 
Or  perhaps  two  sensory  processes  may  be  the  func- 
tions of  one  organ. 

In  certain  diseases  which  affect  the  spinal  cord 
and  roots  of  the  nerves,  we  find  interesting  dissocia- 
tions of  sensation,  differing  from  those  just  de- 
scribed, where  nerves  are  severed  at  some  distance 
from  the  spine.  In  the  degeneration  of  the  spinal 
cord  known  as  syringo-myelia,  all  sensations  of  cold, 
warmth,  and  "sharp  pain"  are  lost  from  large  areas 


SENSATION   QUALITY  05 

of  the  body  without  affecting  touch  or  pressure. 
In  other  diseases  touch  alone  may  disappear,1  and 
in  other  conditions  touch  and  cold  are  lost,  but  not 
warmth  and  heat.  In  some  instances  the  sensibility 
of  the  hairs  alone  has  been  lost. 

ii.  Kinesthetic  and  Coenaesthetic  Sensation 

The  muscular  and  visceral  sensations  furnish  us 
with  another  striking  illustration  of  the  difficulties 
which  beset  psychological  analysis.  The  quali- 
tative distinctions  within  these  classes  are  scientifi- 
cally no  less  important  than  in  the  other  sensory 
groups,  yet  the  distinctions  have  to  go  unmade.  In 
the  case  of  the  muscular  sensations,  we  attend  so 
predominantly  to  what  the  sensations  signify — to 
the  ideas  they  arouse — that  we  are  not  able  to  notice 
adequately  the  sensations  themselves.  Perhaps  the 
ability  to  attend  analytically  to  these  sensations 
would  unfit  the  patient  for  the  simplest  routine  of 
life,  so  important  is  it  that  we  attend  to  what  they 
mean,  rather  than  what  they  are. 

Under  the  head  of  muscular  sensation  we  include 
all  those  which  result  directly  from  muscular  move- 

1  In  the  cases  reported,  however,  it  is  not  certain  whether 
deep  pressure  did  not  go,  too.  Tickle  undoubtedly  was  lost, 
also,  But  no  report  is  made  of  that,  it  being  usually  assumed 
by  the  clinician  to  be  a  form  of  touch. 


96  A    SYSTEM   OF   PSYCHOLOGY 

ment,  excepting  those  already  described  as  dermal 
and  subdermal,  although  touch,  for  example,  is 
aroused  when  the  arm  is  flexed  or  extended.1  We 
include,  therefore,  sensations  produced  by  excita- 
tion of  endings  in  the  muscles,2  in  the  tendons,  and 
in  tissues  near  the  joints.  When  I  raise  my  arm, 
the  contraction  of  the  muscles  excites  the  platelets 
which  are  in  contact  with  its  fibres,  the  change  of 
tension  of  the  tendons  probably  excites  endings 
therein,  and  the  movements  of  the  head  of  the  hu- 
merus in  the  shoulder  socket,  and  of  the  apposed 
surfaces  in  the  elbow  joint,  excite  endings  in  the  tis- 
sues surrounding  them;  and  the  sensation-complex 
resulting  from  all  these  excitations — or  in  the  last 
resort,  from  their  cortical  effects — I  call  the  "  feel- 
ing of  raising  my  arm."  If  the  muscular  contrac- 
tion occurs,  but  the  arm  is  held  by  external  force, 
the  details  of  stimulation  in  muscle  and  joint  are 
somewhat  different;  the  muscle  does  not  change  its 
shape  so  much,  and  certain  nerve  terminals  are 
doubtless  less  stimulated,  others  more  stimulated, 
than  if  the  movement  had  occurred,  the  articular 


1  For  sensory  endings  in  the  muscles,  see  Piersol,  fig.  876. 

2  It  is  possible  that  the  deep  pressure  already  mentioned  is 
really  a  sensation  from  nerve  endings  in  the  muscles,  stirred 
by  the  pressure,  and  ought  to  be  classed  as  muscular  sensa- 
tion;  I  am  at  present  inclined  to  that  opinion. 


SENSATION   QUALITY  07 

surfaces  are  subjected  to  pressure,  not  to  friction. 
This  sort  of  stimulation  arouses,  through  its  brain 
effect,  a  sensation-complex  which  we  call  the  "  feel- 
ing of  effort,"  or  of  "weight." 

Whether  different  qualities  are  produced  from  the 
joints  under  different  conditions,  and  whether  the 
relaxation  of  a  muscle  arouses  a  sensation  of  quality 
different  from  that  excited  by  contraction,  we  can- 
not say.  The  differences  on  which  our  judgments 
depend  may  be  all  the  results  of  combinations  of  a 
single  joint-quality  and  a  single  muscle-quality,  the 
extensities  and  intensities  varying. 

It  is  difficult  to  analyze  the  organic  sensations, 
not  because  we  do  not  attend  directly  to  them,  but 
because  there  is  no  experimental  way  of  varying 
them,  and  they  occur  normally  in  such  regular  com- 
plexes that  the  noting  of  elements  is  almost  im- 
possible. You  must  remember  that  if  we  saw  pur- 
ple only  in  the  hue  called  "magenta,"  and  never  in 
the  hues  nearer  the  spectral  colors,  we  should  proba- 
bly never  guess  that  it  is  red  plus  blue.  So  it  is  with 
nausea,  lassitude,  and  such  organic  contents;  they 
may  be  complexes  of  elements  which  occur  in  dif- 
ferent combinations,  but  so  regularly  that  they 
might  as  well  be  elements,  so  far  as  our  experience 
goes.     We  are  in  much  the  same  position  here  that 


98  A   SYSTEM  OF  PSYCHOLOGY 

we  are  as  regards  odors.  Whether  the  elements  are 
many  or  few,  we  are  unable  to  tell. 

The  organic  sensations  seem  not  to  be  aroused  by 
direct  action  of  external  stimulation,  and  those  tis- 
sues which  possess  this  form  of  sensibility  alone  (as, 
for  instance,  the  peritoneum  covering  the  intestines, 
and  the  intestines  themselves),  may  be  pinched, 
cut,  burned,  or  otherwise  maltreated,  without  the 
production  of  any  sensation.  Even  powerful  intes- 
tinal contractions,  artificially  brought  about,  pro- 
duce no  effect  sensationally.  Yet,  under  certain 
conditions,  which  may,  for  all  we  know,  be  chemical 
stimulations  within  the  tissues,  or  changes  in  the 
channel  of  flow  of  the  nervous  currents  originating 
in  these  tissues,  decided  sensational  results  are  pro- 
duced;  witness  the  juvenile  belly-ache.1 

One  sensation-quality  which  does  not  quite  come 
under  the  above  description,  but  which  ought  per- 
haps to  be  included  under  ccensesthesis,  is  dizziness, 
or  vertigo.  This  is  produced  either  directly  or 
indirectly  by  the  stimulation  of  the  nerve  endings 
in  the  semicircular  canals.  These  canals,  which 
lie  approximately  in  three  planes,  at  right  angles  to 


1  There  is  a  theory  that  belly-ache  is  due  to  the  irritation 
of  the  abdominal  peritoneum,  Avhich  is  sensitive  to  pressure, 
ciit ting,  etc.,  giving  only  a  "painful"  sensation. 


SENSATION    QUALITY  99 

each  other,  and  so  are  sensitive  to  rotation  in  any 
direction,  are  supplied  by  a  branch  of  the  same 
nerve  which  supplies  the  cochlea,  but  the  sensa- 
tions are  by  no  means  auditory.  Pathological  irri- 
tation of  the  semicircular  canals  produces  sympto- 
matic dizziness,  and  if  the  canals  are  completely 
destroyed  the  patient  can  no  longer  be  made  dizzy. 
Dizziness  is  associated  with  various  nervous  phe- 
nomena, notably  the  rhythmic  eye  movements  known 
as  nystagmus  (whirling  until  one  is  dizzy  will  pro- 
duce these  movements),  and  can  be  produced  in 
so  many  ways  (eye  disease,  indigestion,  mental 
shock,  are  some  of  the  ways)  that  any  conclusion  as 
to  the  exact  function  of  the  semicircular  canals  is 
at  present  impossible. 

The  "dark-brown  taste"  to  which  we  have  re- 
ferred earlier  is  perhaps  due  to  excitation  of  nerve 
endings  in  the  mucus  membrane  by  substances 
produced  directly  or  indirectly  as  a  result  of  ab- 
normal chemical  changes  in  the  alimentary  canal. 
In  the  general  organic  feelings  of  well-being,  de- 
jection, placidity,  etc.,  as  well  as  in  more  specific 
emotional  content,  it  is  possible  that  an  important 
causal  factor  is  stimulation  by  chemical  substances 
(hormones)  secreted  by  the  various  ductless  glands, 
and  poured  by  them  into  the  blood. 


100  A   SYSTEM   OF   PSYCHOLOGY 

The  painful  sensation  known  as  ache  is  apparently 
the  function  of  various  tissues  deeper  than  the  skin 
and  mucus  membrane.  It  is  a  true  ccensesthetic 
sensation,  although  seemingly  allied  to  intense  cold. 
This  suggestion  of  cold  is  doubtless  a  matter  of 
association,  cold  being  a  common  cause  of  ache. 


CHAPTER  V 

THRESHOLDS   OF   CONSCIOUSNESS 
I.  Stimulus-Thresholds 

In  order  that  a  stimulus  may  produce  a  sensation 
it  must  satisfy  certain  limiting  conditions  called 
stimulus-thresholds.  These  conditions,  which  are 
strictly  physical,  are  matters  of  (a)  wave  length  or 
molecular  character,  (b)  intensity  or  amount  of  en- 
ergy per  unit  of  time,  and  (<")  duration  of  action  of 
the  stimulus  and  extent  of  area  affected  by  it.  All 
these  conditions  are  capable  of  being  expressed  as 
magnitudes. 

Of  the  first  type  we  have  given  one  illustration 
already,  in  speaking  of  odors,  which  must  have  the 
molecular  weight  of  HCN  at  least.  Probably  sim- 
ilar determinations  may  be  made  for  gustable  sub- 
stances. Light-waves  must  have  a  length  of  not 
greater  than  circa  seventy-five  hundred-thousandths 
of  a  millimeter  (.00075  mm.)  and  not  less  than 
thirty-eight  hundred-thousandths  (.00038  mm.)  in 

order  to  arouse  visual  sensation.      The  longest  air 

101 


102  A    SYSTEM   OF   PSYCHOLOGY 

vibration  which  will  arouse  a  sensation  of  tone 
is  about  twelve  meters,  and  the  shortest  about 
one-half  of  a  millimeter.  These  magnitudes  are 
thresholds. 

If  we  consider  ether-vibrations  of  sufficient  energy 
falling  on  a  normal  retina,  commencing  with  waves 
too  long  to  be  visible  and  steadily  decreasing  in 
length,  we  can  conceive  that  when  a  certain  wave 
length  is  reached  a  sensation  of  light  will  occur;  it 
will  "enter  the  mind"  or  "enter  consciousness"  at 
that  point.  This  point  at  which  the  sensation 
"steps  in"  is  accordingly  dubbed  the  threshold. 
In  the  cases  of  sound  and  light  there  are  two  thresh- 
olds; you  can  approach  the  limits  of  sensibility 
from  either  direction;  and  the  same  may  be  true  of 
smell.  There  may  be  gases  which  are  odorless  be- 
cause their  molecular  weights  are  too  great. 

These  thresholds  are  sometimes — and  incorrectly 
— called  qualitative.  There  is  no  such  thing  as  a 
qualitative  threshold.  Clearness  and  accuracy  can 
be  attained  by  referring  to  the  auditory  wave-fre- 
quency thresholds,  the  visual  wave-length  thresh- 
olds, etc. 

The  second  sort  of  thresholds  occur  in  the  series 
of  intensities  of  stimulations,  and  this  sort  of  thresh- 
old is  always  meant  by  the  term  when  not  expressly 


THRESHOLDS   OF   CONSCIOUSNESS  103 

qualified  to  signify  otherwise.  These  thresholds 
may  be  referred  to  as  the  acoustical  intensity-thresh- 
old, the  optical  intensity-threshold,  etc. 

The  acoustical  and  optical  intensity-thresholds 
are  theoretically  measurable  as  certain  amplitudes 
of  waves  of  a  given  length  (see  next  chapter),  but 
practically  they  are  measured  in  a  much  more 
primitive  way.  The  acoustical  threshold  is  ex- 
pressed as  the  distance  through  which  a  given  ball 
must  be  dropped  on  a  given  plate  or  block,  at  a 
given  distance  from  the  ear,  in  order  to  produce  an 
auditory  sensation.  The  optical  threshold  is  usu- 
ally determined  by  finding  the  proportion  in  which 
a  given  beam  of  light  may  be  reduced,  and  yet 
arouse  a  visual  sensation.  As  might  be  expected, 
such  determinations  are  not  very  satisfactory. 

The  osmical  threshold  is  accurately  determined 
by  finding  the  least  amount  of  a  given  substance 
which,  infused  in  a  unit  quantity  of  dry  air,  will 
produce  the  appropriate  sensation  under  the  best 
conditions  of  inhalation.  So  the  geusical  threshold 
is  determined  by  finding  the  least  amount  of  sub- 
stance which,  dissolved  in  a  unit  quantity  of  dis- 
tilled water,  will  arouse  taste  sensations. 

The  haptic  threshold  is  determined  by  laying 
weights  on  the  skin  or  by  pressing  it  with  delicate 


104  A    SYSTEM   OF   PSYCHOLOGY 

.springs  of  metal  or  hair,  giving  known  amounts 
of  pressure.  The  hapto-algetic  threshold  may  be 
similarly  measured  by  finding  the  least  pressure  on 
a  given  area  producing  "pain."  The  intensity- 
threshold  for  warmth  and  cold  cannot  be  meas- 
ured adequately  by  any  simple  method. 

The  stimulus  acting  on  any  organ  must  act  for  a 
certain  length  of  time  before  a  sensation  is  produced, 
and,  if  the  intensity  is  low,  a  duration  may  be  found 
which  will  allow  no  sensation  to  be  raised  into  con- 
sciousness. A  light,  intense  enough  to  be  clearly 
seen  under  ordinary  conditions,  may  remain  invisible 
when  allowed  to  fall  on  the  retina  for  only  a  few 
thousandths  of  a  second.  Conceivably,  this  dura- 
tion-threshold is  only  an  aspect  of  the  fundamen- 
tal intensity-threshold;  for  the  energy  applied  in 
the  brief  time  measured  by  the  duration-threshold 
is  just  sufficient  to  raise  the  neural  process  to  the 
point  at  which  a  sensation  is  produced. 

The  area-threshold  of  stimulation,  which  is  im- 
portant only  in  vision,  is  doubtless  also  of  deriva- 
tive nature,  the  energy  being  distributed  over  an 
area  wider  than  that  mathematically  correspond- 
ing to  the  external  object  or  its  projection  on  the 
organ. 


THRESHOLDS   OF   CONSCIOUSNESS  105 

2.  Stimulus  Difference  Thresholds 

Two  stimuli  may  be  different  in  intensity,  in 
wave  length,  in  duration,  or  in  some  other  feature, 
and  yet  there  may  be  no  difference  noticeable  in 
the  sensations  corresponding  to  the  stimuli.  So 
far,  it  is  an  open  question  whether  this  failure  to 
observe  a  difference  in  the  given  respect  means  that 
the  sensations  are  really  the  same  in  that  respect, 
or  whether  they  are  necessarily  different  (assum- 
ing that  the  conditions  of  the  organ  and  environ- 
ment are  equivalent,  except  in  respect  to  the  differ- 
ence of  stimulus  under  consideration).  The  fact 
remains  that  a  certain  measurable  difference  in 
stimuli  is  necessary  in  order  that  a  corresponding 
difference  may  be  perceived  in  sensation.1  The 
magnitude  of  this  required  difference  is  called  the 
difference  threshold.  The  difference  threshold  is 
usually  expressed  as  the  increment  or  decrement 
which  must  be  made  to  any  stimulus  before  the  in- 
creased or  decreased  stimulus  produces  a  sensation 
differing  in  the  corresponding  way  from  the  sensa- 
tion produced  by  the  original  or  "standard  stimu- 
lus." 


1  This  statement  is  subject  to  the  consideration  of  the 
"Constant  Error."     See  next  section. 


106  A   SYSTEM   OF   PSYCHOLOGY 

3.  Other  Thresholds 

There  are  other  thresholds  which  we  have  not 
considered  above.  Note  that  we  have  so  far 
been  dealing  with  the  stimulus-threshold,  or  the 
stimulus  difference  threshold.  They  are  some- 
times called  "sensation-thresholds,"  but  the  other 
designation  is  the  accurate  one.  They  are  always 
determined  by  the  measurement  of  stimuli  which 
produce  a  specified  effect  before  consciousness. 
There  are  other  thresholds  which  are  not  the 
measurements  of  stimuli  at  all. 

We  may  determine,  for  example,  the  least  time 
interval  perceptible  as  such;  or  the  least  space  in- 
terval in  touch  or  vision.  Or  we  may  determine  the 
difference  threshold  for  time  intervals.  These  mat- 
ters are  not  relevant  here  except  to  forestall  the  sup- 
position that  all  thresholds  are  stimulus-thresholds. 

4.  The  Constant  Error 

Suppose  I  wish  to  find  the  stimulus  difference 
threshold  for  intensity  (which  for  brevity  we  may 
call  the  I.  D.  T.),  for  a  pressure  of  twenty-five 
grams  on  the  centre  of  the  palm  of  the  hand.  Ob- 
viously, the  general  method  of  procedure  must  be  to 
place  on  the  selected  spot  of  the   patient's   hand 


THRESHOLDS   OF   CONSCIOUSNESS  107 

a  weight  of  twenty-five  grams,  alternating  with 
weights  slightly  greater  and  slightly  less,  until  we  find 
the  least  weight  which  is  felt  as  heavier,  and  the 
greatest  which  is  felt  as  lighter,  than  the  twenty-five- 
gram  ("Standard")  weight.  The  elaborate  tech- 
nic  and  many  precautions  necessary  to  make  our 
results  significant,  we  need  not  describe  here,  but 
one  feature  of  the  experiment  is  of  present  impor- 
tance: If  the  "Standard"  weight  is  given  first  in 
each  case,  and  the  second  weight  ("Variable")  is 
varied  appreciably,  the  patient  (who,  of  course,  is 
not  allowed  to  see  the  hand  and  weights,  and  is  not 
informed  as  to  their  actual  weight  values),  will  in 
very  many  cases  declare  the  "Variable"  heavier 
or  lighter  than  the  "Standard",  when  the  two  are 
exactly  equal.  You  may  find  at  the  end  of  your 
experiment,  for  example,  that  the  weight  which  is 
on  the  average  just  perceptibly  heavier  than  the 
"Standard,"  when  the  "Standard"  is  given  first,  is 
actually  lighter  than  the  "Standard"!  But  this 
disconcerting  result  is  not  at  all  erroneous  or 
troublesome.  If  you  make  an  equal  number  of 
experiments  with  the  "Variable"  first  and  the 
"Standard"  last,  you  may  find  the  results  the  con- 
verse of  the  first  set — the  just  perceptibly  lighter 
weight  being  now  heavier  than   the  "Standard." 


108  A   SYSTEM   OF   PSYCHOLOGY 

hi  short,  your  results  include  two  factors;  the 
I.  D.  T.,  and  the  constant  error  (C.  E.)  due  to  the 
order  of  the  weights.  The  second  of  two  weights 
is  not  judged  under  the  same  conditions  as  is  the 
first,  and  vice  versa.  You  must  always  make  ex- 
periments in  both  time  orders  (S-V  and  V-S),  and 
by  comparing  the  results  in  the  two  cases  determine 
the  C.  E.  of  time  order,  before  you  can  determine 
the  approximate  D.  T. 

Constant  errors,  due  to  all  sorts  of  factors,  con- 
tribute to  the  complexity  of  the  problems  of  experi- 
mental psychology,  and  in  many  cases  the  determi- 
nation of  the  magnitude  of  the  C.  E.  under  definite 
conditions  becomes  a  method  of  solving  important 
problems. 


CHAPTER    VI 

SENSATION-INTENSITY 
i.  Intensity  of  Sensation  and  Intensity  of  Stimulus 

As  we  have  already  implied,  the  intensity  of  sen- 
sation depends  in  general  on  the  intensity  of  the 
process  in  the  end-organ  and  brain,  which  in  turn 
depends  in  part  on  the  intensity  of  the  physical 
stimulus.  There  are,  therefore,  two  relations  to  be 
considered:  (1)  the  relation  between  the  stimulus 
and  the  nervous  process,  and  (2)  the  relation  be- 
tween the  nervous  process  and  the  sensation.  Con- 
cerning each  of  these  relations  we  have  practically 
nothing  but  the  bare  fact  that,  ceteris  paribus,  an 
increase  in  the  intensity  of  one  is  connected  with 
an  increase  in  the  intensity  of  the  others. 

The  condition  of  the  sense-organ  has  an  important 
influence  on  the  intensity  of  the  sensation  result- 
ing from  a  given  stimulation:  fatigue  and  adaptation 
can  modify  the  result  immensely.  Thus,  the  light 
sensation  aroused  by  light  striking  the  dark-adapted 
eye  may  be  very  much  brighter  than  the  sensation 

aroused  by  a  light  many  times  more  intense  acting 

109 


110  A    SYSTEM   OF   PSYCHOLOGY 

on  the  light-adapted  eye.  These  facts  do  not  offer 
any  serious  logical  obstacle  to  the  formulation  of 
statements  of  intensity  relation,  as  all  such  are  sim- 
ply required  to  specify  that  the  relation  holds  only 
for  a  uniform  condition  of  the  sense-organ  and 
nervous  connections;  but  they  introduce  serious 
practical  difficulties,  because  it  is  not  always  possi- 
ble to  ascertain  whether  the  condition  of  an  organ 
is  uniform  during  any  given  period  of  experimenta- 
tion. 

The  difficulty  of  the  discovery  of  definite  inten- 
sity relationships  of  sensation  and  stimulus  is  in- 
creased by  the  difficulty  of  estimation.  Direct  meas- 
urement of  sensation-intensities  is  impossible.  We 
can  only  compare  one  sensation  with  another,  and 
determine  which  of  the  two  is  more  intense.  And 
this  determination  is  strictly  relative.  The  apparent 
intensity  of  a  sensation  is  affected  by  other  sensa- 
tions, aside  from  any  change  in  the  actual  intensity 
of  the  sensation.  For  instance:  a  candle  burning 
near  a  coal-oil  lamp  seems  dimmer  than  the  same 
candle  burning  beside  the  flame  of  a  minute  gas- 
jet;  yet,  if  the  experiment  is  performed  in  moder- 
ate daylight,  the  candle  flame  is  practically  as 
bright  sensationally  in  the  one  case  as  in  the  other. 
When  the  time  factor  enters,  and  sensations  pres- 


SENSATION-INTENSITY  1 1 1 

ent  are  compared  with  past  sensations,  the  relativity 
of  the  judgment  of  comparison  becomes  greater. 
But  even  when  the  time  factor  is  not  present, 
the  comparison  of  sensations  of  any  sense  is  rel- 
ative. 

Taking  into  account  the  relativity  of  sensations 
and  the  relativity  of  the  estimation  of  sensations, 
we  find  difficulties  enough  to  account  for  the  fact 
that  no  laws  of  the  quantitative  relation  of  stimulus- 
intensity  to  sensation-intensity  are  discoverable  at 
present.  The  nearest  approach  to  a  law  of  this  kind 
is  "Weber's  Law,"  which  deals  with  the  intensity 
difference  threshold  only. 

2.  Weber's  Law 

If  we  express  the  intensity  D.  T.  as  a  ratio  of 
the  just  perceptible  increment  (or  decrement)  to 
the  Standard,  we  may  state  Weber's  Law  in  the 
following  terms:  The  I.  D.  T.  for  different  values 
of  a  standard  stimulus  varying  in  intensity  only  is 
practically  constant  if  the  general  condition  of  con- 
sciousness remains  the  same.  This  law  holds,  how- 
ever, only  for  mean  ranges  of  intensity;  for  feeble 
or  very  high  intensities  it  is  invalid. 

Weber's  Law  may  be  expressed  less  technically, 
but  yet  accurately,  as  follows:     The  ratio  of  the 


112  A   SYSTEM  OF  PSYCHOLOGY 

intensity  of  a  standard  stimulus  to  the  just  percepti- 
ble increment  in  intensity  is  the  same  as  the  ratio 
of  the  intensity  of  any  other  standard  to  its  just 
perceptible  increment  (or  decrement),  provided 
the  sensations  aroused  by  the  two  standards  differ 
only  in  intensity,  and  provided  that  the  general 
mental  and  physical  condition  of  the  patient  is  the 
same  in  the  tests  with  the  different  standards.  There 
will  be  in  any  case  a  minimum  standard  and  a 
maximum  standard,  below  which  and  above  which, 
respectively,  the  equality  will  not  hold. 

As  a  concrete  example  of  the  uniformity  described 
by  Weber's  Law,  we  may  give  the  following.  If  the 
pressure  of  fifty  grammes  on  the  finger  needs  to  be 
increased  to  fifty-one  grammes  in  order  that  the  in- 
crease may  be  noted,  the  pressure  of  one  hundred 
grammes  will  need  to  be  increased  to  one  hunderd 
and  two.  In  other  words,  the  I.  D.  T.  at  fifty 
grammes  (^o)  is  the  same  as  the  I.  D.  T.  at  one 
hundred  grammes  (ttj)-  Above  perhaps  four  hun- 
dred grammes,  and  below  perhaps  ten  grammes,  the 
ratio  will  be  somewhat  different. 

The  provisions  to  which  we  have  given  place  in 
the  formulations  are  exceedingly  important.  Among 
other  cases  in  which  these  provisions  preclude  our 
expecting  the  I.  D.  T.'s  to  be  equal,  the  following 


SENSATION-INTENSITY  113 

may  be  noted:  (1)  Different  senses,  or  different 
qualities;  thus,  we  would  not  expect  to  find  the 
I.  D.  T.  for  sugar  the  same  as  that  for  blue  light, 
or  even  for  salt.  (2)  Different  individuals.  (3) 
Different  portions  of  the  sense-organ,  as  the  centre 
and  periphery  of  the  retina.  (4)  Different  exten- 
sities  or  durations  of  sensation.  (5)  Different  con- 
ditions of  the  patient,  as  rested  and  fatigued.  In 
addition,  we  do  not  find  a  constant  D.  T.  for  any 
other  character  than  intensity.  Weber's  Law  has 
no  bearing  on  the  D.  T.  for  color  change  (wave 
length),  or  pitch,  or  duration.  It  applies  to  inten- 
sity only. 

Weber's  Law  was  given  its  name  in  honor  of 
E.  H.  Weber,  who  first  discovered  the  facts  which  it 
describes.  The  first  formulation,  and  the  appli- 
cation of  the  name,  were  the  work  of  G.  T.  Fech- 
ner,  who  attempted  to  give  the  law  an  application 
to  stimulus  differences  greater  than  those  just  per- 
ceptible, and  to  turn  it  into  a  statement  of  the  re- 
lation of  stimulus-intensity  to  sensation-intensity. 
Fechner's  attempt,  based  on  the  assumption  that  all 
just-perceptible  differences  in  sensation  are  equal, 
resulted  in  "Fechner's  Law,"  and  "Fechner's 
Formula,"  which  expressed  the  relation  as  a  logarith- 
mic equation.     The  discussions,  controversies,  and 


114  A    SYSTEM    OF    PSYCHOLOGY 

investigations  consequent  on  this  formulation  con- 
stitute the  subject  sometimes  called  psycho-physics. 
Fortunately  for  the  student,  the  whole  matter  is 
chiefly  of  historical  importance,  and  may  be  safely 
ignored  in  an  elementary  course.1 

3.  The  Comparison  of  Intensity  Differences 

The  determination  of  the  just  perceptible  differ- 
ence involves  an  equating  of  intensities.  In  order 
to  find  what  intensities  seem  equal  to  a  given  inten- 
sity, we  must  find  the  greatest  which  seems  less  and 
the  least  which  seems  greater;  conversely,  in  de- 
termining these  thresholds,  we  have  substantially 
determined  the  intensity  equivalents.  In  addition 
to  finding  equal-seeming  intensities  of  sensation  we 
may  also  compare  differences  of  intensity  with  re- 
gard to  their  equality  or  non-equality;  but  we  find 
that  the  results  of  these  judgments  are  less  uniform 
than  those  of  mere  intensity. 

If  we  find  two  sensations,  Si  and  S2,  which  ap- 

1  The  analytically  inclined  student  may  be  disturbed  by 
the  careless  way  in  which  we  speak  of  the  discriminating  of 
differences  of  stimuli,  instead  of  the  discriminating  of  differ- 
ences of  sensation  corresponding  to  certain  differences  of  stim- 
uli. We  trust,  however,  that  the  discussion  gains  in  simplic- 
ity without  losing  in  clearness  by  that  looseness. 

For  an  adequate  discussion  of  Fechner's  addition  to  Weber, 
see  James,  Principles  of  Psychology,  vol.  I,  chap.  XIII,  pp. 
533-549. 


SENSATION-INTENSITY  115 

pear  exactly  as  different  in  intensity  as  two  other 
sensations,  S3  and  S4,  we  might  expect  to  find  on  the 
analogy  of  Weber's  Law,  that  the  stimuli  of  the 
first  pair  have  the  same  intensity-ratio  as  the  stimuli 
of  the  second  pair.  Letting  the  intensity  of  the 
stimulus  be  represented  by  R,  the  relation  in  ques- 
tion may  be  expressed,  Ri/R2  =  R3/R4.  This  rela- 
tion, which  is  demanded  by  Fechner's  Formula, 
is  actually  found  to  hold  in  many  cases.  In  other 
cases,  however,  the  relation  has  been  found  to  be 
more  nearly  that  of  equality  of  stimulus  differences; 
Ri  — R2  =  R3— R4,  and  this  divergence  has  given  rise 
to  some  acrimonious  controversy  over  the  "correct- 
ness" of  the  one  result  or  the  other.  As  a  matter 
of  fact,  both  are  correct.  Some  individuals  will 
rather  uniformly  select  "equalities"  of  the  first 
type,  and  other  individuals  will  select  equalities  of 
the  second  type.  Certain  individuals  will  select 
neither  type  of  equality,  and  still  others  will  select 
both.1 

1  In  extensive  experiments  on  nearly  sixty  persons,  using 
the  same  apparatus  and  same  conditions  throughout,  I  have 
found  that  in  selecting  a  light-brightness  or  weight-intensity 
which  seemed  midway  between  two  standard  light  or  pressure 
intensities,  the  persons  fell  into  four  classes:  (1)  Those  who 
selected  the  geometrical  mean;  (2)  those  who  selected  the 
arithmetical  mean;  (3)  those  who  selected  a  mean  which  was 
the  arithmetical  mean  of  the  geometrical  and  arithmetical 
mean;    (4)  those  who  selected  approximately  the  harmonic 


116  A    SYSTEM    OF   PSYCHOLOGY 

4.  The  Relativity  of  Sensation 

The  relativity  of  sensation-intensity  and  inten- 
sity-differences; their  variability,  that  is,  according 
to  the  various  conditions  mentioned  in  the  preced- 
ing sections,  may  account  for  the  apparent  "rela- 
tivity" of  sensation-quality,  which  is  usually  in- 
cluded by  specification  or  implication  in  references 
to  the  "relativity  of  sensation."  It  is  often  implied 
that  the  quality  of  a  sensation  is  not  determined  by 
a  definite  stimulus  acting  on  a  corresponding  ner- 
vous mechanism,  but  by  this  action  in  conjunction 
with  all  the  other  nervous  and  mental  activities. 
Color  contrast,  and  all  the  other  conditions  in  which 
now  this  sensation,  now  that,  are  gotten  from  the 
same  stimulus  under  different  conditions,  are  cited 
in  support  of  this  view.  These  phenomena  may 
not  be  due  to  qualitative  variability  at  all,  but  sim- 
ply to  the  variability  of  intensity. 

A  qualitative  change  in  a  sense-content  may  be 
one  of  three  things.  (1)  It  may  be  a  change  in  the 
intensity  or  intensities  of  one  or  more  of  the  quali- 

mean.  Some  of  the  persons  were  too  irregular  to  be  fairly 
classified  at  all,  a  few  alternated  between  two  types,  and  one 
person  insisted  on  selecting  two  means,  approximately  the 
arithmetical  and  geometrical,  which  he  insisted  were  both 
good,  although  not  "of  the  same  sort." 


SENSATION-INTENSITY  117 

tative  elements  present  in  the  content.  (2)  It  may 
be  the  addition  of  a  qualitative  element,  or  of 
qualitative  elements  not  previously  present.  (3)  It 
may  be  a  simulation,  due  to  a  direction  of  the  atten- 
tion more  strongly  or  less  strongly  to  certain  ele- 
ments. 

A  sensation  of  pure  red  (if  such  is  obtainable) 
may  become  more  intense,  or  less  intense,  and  may 
completely  disappear;  but,  so  long  as  it  remains,  it 
can  be  nothing  but  red.  The  same  stimulus  which 
now  arouses  pure  red  may,  in  a  different  condition 
of  the  eye,  arouse  some  blue  also;  in  which  case  the 
result  is  purplish.  So  daylight,  which  "normally" 
excites  the  three  colors  in  such  proportions  of  in- 
tensity that  "white"  results,  may,  if  the  eye  is 
adapted  to  purple  light,  excite  the  green  process 
with  unusual  intensity;  hence,  the  green  after-image. 
Distilled  water  does  not  ordinarily  excite  the  taste- 
buds,  and  hence  there  is  no  gustatory  sensation; 
but  by  the  previous  action  of  some  drug  the  nerve 
endings  may  be  made  sensitive  to  the  effect  of  the 
water;  this  is,  in  effect,  the  lowering  of  the  stimulus- 
threshold. 


118  A    SYSTEM   OF   PSYCHOLOGY 

5.  Beats 

An  important  phenomenon  of  intensity  in  the 
auditory  realm  is  that  of  beats.  Beats  are  periodic 
fluctuations  in  the  intensity  of  a  sound,  commonly 
arising  when  the  stimulus  (air-waves)  is  composed 
of  vibrations  from  two  separate  sources,  as  two 
tuning-forks,  or  pipes,  or  strings,  giving  notes  of 
proper  pitches.  Two  sources  of  sound  will  give 
rise  to  beats  if  (1)  the  note  of  one  is  less  than  (circa) 
thirty  vibrations  per  second  faster  than  the  other, 
or  (2)  when  twice  the  rate  of  the  lower  is  less  than 
thirty  vibrations  faster  or  slower  than  the  other. 
These  beats  are  called  beats  of  the  first  and  second 
orders  respectively.  Beats  of  the  third  and  higher 
orders  exist  theoretically,  but  are  so  weak  as  to  be 
practically  negligible.  For  the  physical  theory  of 
the  interference  of  the  sound-waves,  which  produces 
the  alternate  maxima  and  minima  corresponding 
to  the  beats  in  sensation,  the  student  may  refer  to 
any  good  treatise  on  sound,  or  on  general  physics. 

A  single  source  of  sound,  as,  c.  g.,  a  bell,  may  pro- 
duce beats  through  the  interference  of  the  partial 
tones  contained  in  its  note.  It  is  this  which  gives  the 
tremulous  character  to  the  sound  of  a  bell.  Alter- 
nate reinforcement  and  diminution  of  the  intensity 


SENSATION-INTENSITY  1 10 

of  a  single  note  may  be  produced  also  by  various 
extrinsic  means.  Tune  a  bottle  to  the  note  of  a 
tuning-fork  by  pouring  in  water  to  the  right  height, 
and  then  rotate  the  fork,  holding  it  horizontally  over 
the  mouth  of  the  bottle:  the  beats  thus  produced 
are  of  the  same  character  as  those  produced  by  two 
forks  sounding  together.  The  vibrato  or  tremolo 
of  the  human  voice,  which  is  an  effective  embellish- 
ment when  used  sparingly,  and  which  mediocre 
singers  employ  without  reason  or  mercy,  is  in  some 
cases  purely  a  matter  of  intensity-variation,  L  c, 
beats;  in  other  cases  (in  most  cases,  in  fact)  it  is 
partly  a  matter  of  pitch  changes. 


CHAPTER    VII 

PROTENSITY  AND  EXTENSITY  OF  SENSATION 
i.  The  Duration-Character 

The  duration  or  protensity  of  a  sensation  is  to  be 
discriminated  from  the  duration  of  the  experience, 
and  from  the  duration  of  the  stimulus.  A  stimulus 
acting  one  second  may  produce  a  sensation  lasting 
less  than  a  second  or  more  than  a  second.  The 
sensation  may  not  be  experienced  during  a  certain 
period  of  its  existence;  perhaps  it  may  not  be  ex- 
perienced at  any  time;  at  least  there  are  sensations 
which  are  unnoticed  during  a  part  or  the  whole  of 
their  existences.  We  cannot  say  with  certainty  that 
any  sensation  is  experienced  from  beginning  to  end; 
perhaps  all  sensations  have  unexperienced  phases. 
Even  if  we  should  admit,  as  certain  metaphysicians 
would  have  us  do,  that  the  duration  of  the  sensation 
and  the  duration  of  the  experience  of  the  sensation 
are  equal  and  coterminous,  we  should  still  be  obliged 
to  hold  that  the  duration  of  the  one  is  logically  dis- 
tinct from  the  duration  of  the  other,  for  the  duration 

which   is  characteristic  of  the  sensation  is  actually 

120 


PROTENSITY   AND   EXTENSITY  121 

experienced  along  with  the  other  characters  (quality, 
intensity,  etc.).  In  other  words,  the  duration  ex- 
perienced is  not  the  same  thing  as  the  experience  of 
the  duration. 

The  protensity  or  duration  of  the  sensation  as  di- 
rectly experienced  is  distinguished  from  the  duration 
as  measured  by  its  relation  to  series  of  other  events, 
whether  these  events  are  other  sensations  directly 
experienced  (as  in  the  immediate  estimate  of  time) 
or  whether  they  are  members  of  an  ideal  series 
based  on  mathematical  subdivisions  of  the  parallel 
of  latitude  (minutes  and  seconds).1 

It  is  the  duration  of  sensation  as  an  experienced 
fact  to  which  we  refer  in  speaking  of  the  protensity 
or  duration-character.  A  sensation  without  it  could 
never  be  brought  into  the  time  relation,  and  time,  as 
we  experience  it,  could  not  exist  apart  from  sensa- 
tions. Time,  however,  involves  more  than  sensa- 
tion-duration, as  we  will  see  later. 

The  direct  comparison  of  two  sensation-durations 
is  much  more  difficult  than  the  comparison  of  in- 
tensities.    In  the  first  place,  it  is  impossible  to  ex- 

1  This  mathematical  relation  of  sensation-duration  to  a 
standard  time  series  is  often  loosely  designated  the  "  duration 
of  sensation"  as  distinguished  from  the  "experience  of  the 
duration,"  the  last  name  heing  applied  uncritically  to  the 
duration-character  of  the  sensation,  the  estimated  duration, 
11 1 it i  tlic  experience  of  these. 


122  A   SYSTEM  OF   PSYCHOLOGY 

elude  a  multitude  of  other  sensations  (bodily,  etc.) 
which  insist  on  taking  a  part  in  the  comparison. 
In  the  second  place,  since  in  most  cases  the  dura- 
tions compared  must  be  in  succession,  the  memory 
factor  becomes  especially  disturbing.  For  these 
reasons,  very  little  has  actually  been  accomplished 
in  the  investigation  of  the  difference-sensibility  for 
protensity,  although  there  has  been  a  great  deal  of 
experimentation  in  the  general  field  of  time-content. 

2.  Extensity 

Extensity  is  related  to  space  as  protensity  is  to 
time.  In  each  case  the  sensation-character  is  so 
intimately  built  up  into  the  complex  that  it  is  diffi- 
cult to  analyze  it  out;  but  the  analysis  is  the  less 
difficult  in  the  case  of  extensity. 

Extensity  can  best  be  demonstrated  in  the  dermal 
sense.  Provide  yourself  with  a  small  cork  stopper 
and  a  small  wooden  rod  with  a  blunt,  very  slightly 
rounded  point.  Touch  your  wrist  or  lower  arm  alter- 
nately with  the  rod  and  with  the  cork,  avoiding  hairs 
and  veins,  and  pressing  just  hard  enough  to  arouse 
touch  sensations.  Notice  that  the  touches  have 
different  "  bigness",  although  neither  has  any  space- 
form;  that  is,  you  cannot  discriminate  any  parts  in 
cither;  you  cannot  discriminate  edge  from  middle, 


PROTENSITY   AND   EXTENSITY  123 

or  one  side  from  the  other.  The  difference  which 
you  observe  is  one  of  extensity.  In  a  corresponding 
way,  extensity-differences  may  be  demonstrated  in 
the  visual  field. 

Extensity-differences  depend  physiologically  on 
differences  in  the  number  of  nerve  endings  stimu- 
lated. In  general,  the  more  nerve  endings  stimu- 
lated, the  more  extensive  the  sensation,  but  we  can- 
not expect  to  find  any  definite  relation  of  number 
to  extensity  which  would  hold  for  different  parts  of 
the  organism,  or  even  for  different  parts  of  a  sense 
organ.  Extensity-differences  occur  wherever  there 
are  nerve  endings  capable  of  stimulation  in  different 
numbers,  as  in  the  senses  of  vision,  touch,  warmth, 
cold,  and  bodily  feeling.1 

In  the  case  of  auditory  sensations,  the  extensity, 
if  it  exists,  is  probably  that  which  we  commonly 

1  The  difference  in  volume  between  different  aches,  for 
example,  is  often  noticed.  In  smelling,  it  is  possible  that 
practically  the  whole  group  of  nerve  endings  which  are  ca- 
pable of  responding  to  a  given  odor  are  stimulated  every  time 
the  odor  is  aroused,  as  we  find  no  pronounced  differences  of 
extensity  with  any  one  odor.  Whether  different  odors  have 
different  extensities  we  cannot  say  conclusively.  The  sen- 
sations of  smell,  nevertheless,  have  extensity,  even  though 
differences  therein  are  obscure;  it  is  the  apparent  (or  real) 
sameness  or  the  practical  unimportance  of  differences,  which 
makes  us  overlook  the  character  in  olfactory  experience.  Yet 
we  ought  not  to  say  even  that  it  is  practically  unimportant, 
until  we  are  certain  that  it  plays  no  part  in  the  puzzling  com- 
position of  odors. 


124  A    SYSTEM   OF   PSYCHOLOGY 

call  'pitch.  The  nerve  endings  (the  hair-cells)  in  the 
cochlea  of  the  ear  form  a  linear  series  (or  multiple 
linear  series)  running  the  length  of  the  basilar  mem- 
brane, and  it  is  probable  that  high  notes  (rapid  vi- 
brations) stimulate  only  the  cells  situated  at  the 
end  nearer  the  middle  ear;  lower  notes  (slower  vi- 
brations) stimulating  a  larger  number.  It  is  well 
known  that  the  destruction  of  the  cochlear  nerve 
endings  nearest  the  middle  ear  (at  the  basal  extrem- 
ity of  the  basilar  membrane)  destroys  the  sensitiv- 
ity of  the  ear  for  high  tones,  but  not  for  low  ones, 
and  this  agrees  well  with  the  extensity  theory,  but 
with  no  other  except  that  of  Helmholtz. 

The  introspective  fact  that  the  difference  between 
low  and  high  tones  seems  like  the  difference  of  ex- 
tensity  of  other  sensations;  the  fact  that  the  sound- 
ing of  a  low  tone  obscures  a  feeble  high  tone,  while 
the  sounding  of  a  high  tone  does  not  obscure  a 
feeble  low  tone;  the  fact  that  the  highest  audible 
tone,  no  matter  what  its  actual  pitch,  always  seems 
"approximating  zero,"  that  is,  having  no  conceiv- 
able terms  beyond  it  in  the  pitch  series;  these  and 
other  facts  point  to  the  correctness  of  the  pitch-ex- 
tensity  theory. 

Pitch  is  no  more  noticed  habitually  as  a  mere 
sensation-character    than   an'   extensities    of  other 


PROTENSITY   AND   EXTENSITY  125 

sensations.  We  do  not  weave  it  into  a  space  system, 
probably  because  of  the  lack  of  muscular  adjust- 
ments for  that  function,  but  we  do,  nevertheless,  or- 
ganize the  different  extensities  in  the  usual  mathe- 
matical way.  One  result  of  the  organization  is  the 
musical  scale,  and  we  normally  perceive  tones  in 
the  scale  relation,  although  usually  not  with  mathe- 
matical exactness.  Exactness  is  attainable  for 
theoretical  purposes,  just  as  exact  space  measure- 
ments are  possible  in  spite  of  the  fact  that  our 
ordinary  estimations  of  space  "by  eye"  are  mere 
approximations  to  accuracy. 

3.  Overtones  and  the  Musical  Scale 

The  method  in  which  the  diatonic  scale  which  we 
use  (in  theory)  at  present,  and  the  modifications  of 
it  employed  in  musical  practice,  were  developed,  is 
an  interesting  and  important  chapter  in  the  psychol- 
ogy of  auditory  sensation,  but  a  chapter  which  can 
only  be  sketched  at  present.  The  scale  has  de- 
veloped through  the  need  of  conforming  to  the 
natural  series  of  overtones  or  partial  tones  (see  be- 
low), the  advantage  of  avoiding  beats,  and  the 
simplicity  of  wood-wind  instruments  with  regularly 
spaced  finger-holes  (primitive  flutes),  these  instru- 
ments giving  scales  which  are  "near "-diatonic. 


126  A    SYSTEM   OF   PSYCHOLOGY 

Overtones,  or  partials,  are  tones  that  sound  along 
with  the  proper  or  fundamental  tone  of  a  source  of 
sound;  or,  rather,  they  are  components  in  the  total 
note,  which  are  higher  in  pitch  than  the  principal 
component  or  fundamental.  Partials  of  various 
number  are  produced  by  all  the  common  sources  of 
sound,  and  may  be  easily  demonstrated  with  an  in- 
strument of  the  "sonometer"  type;  a  long  gut  or 
piano  wire  stretched  on  a  sounding-board  or  box. 
Strike  the  string  with  a  piano  hammer  (a  small  rod 
wrapped  with  cloth  will  do)  at  a  point  one-quarter 
the  distance  from  one  end  to  the  other,  and  then 
touch  it  lightly  in  the  middle  with  a  feather  or  small 
wad  of  cotton;  the  fundamental  note  of  the  string 
will  stop,  but  a  note  an  octave  higher  will  continue 
sounding.  This  octave  tone  is  called  the  first  over- 
tone, or  the  second  partial  (the  fundamental  being 
the  first  partial).  Strike  the  string  at  one-sixth  and 
touch  at  one-third,  and  you  will  hear  the  third 
partial.  Strike  at  one-eighth  and  touch  at  one- 
quarter,  and  you  hear  the  fourth  partial.  If  you 
touch  where  you  have  struck,  the  partial  correspond- 
ing to  the  point  of  touching  will  not  be  produced,  or 
will  be  very  faint;  this  shows  that  it  is  the  striking 
and  not  the  subsequent  touching  that  produces  the 
partial;   which  means  that  the  upper  partial  is  pro- 


PROTENSITY   AND   EXTENSITY  127 

duced  along  with  die  fundamental.  With  a  little 
practice  you  can  in  fact  soon  acquire  the  ability  to 
pick  out  the  partials  without  touching  or  stopping 
the  string. 

In  instruments  of  the  horn  or  trumpet  type,  with 
proper  blowing  and  without  manipulation  of  the 
valves  or  slides,  the  partials  up  to  the  eighth  or 
ninth  may  be  made  to  sound  without  the  partials 
below  the  particular  one  sounded  in  each  case. 
This  gives  a  sort  of  scale  whose  notes  are  far  apart 
at  the  bottom  and  closer  at  the  top,  and  in  this  scale 
we  can  play  the  melodies  known  as  "bugle  calls." 
Since  these  notes  (with  a  modification  of  the  sev- 
enth) are  included  in  the  diatonic  scale  (in  the  brass 
instruments  of  the  modern  orchestra  we  simply  add 
the  intermediate  notes  by  manipulation  of  the  valves 
or  slides)  we  may  reasonably  suspect  that  such 
wind  instruments  have  been  important  in  fixing  the 
notes  of  the  modern  scale. 

In  another  way  the  partials  have  helped  to  fix 
the  intervals  of  the  scale,  especially  the  octave,  the 
interval  between  the  fundamental  and  the  second 
partial,  which  is  relatively  strong  in  the  human 
voice.  In  a  room  or  cave  some  of  the  notes  pre- 
viously sung  are  still  vibrating  while  another  is 
being  sung  (or  played)  so  that  the  present  note  must 


128  A    SYSTEM   OF   PSYCHOLOGY 

"harmonize"  with  the  overtones  of  the  previous 
note. 

The  musical  interval  between  two  notes  is  meas- 
ured by  the  ratios  of  the  vibration-frequencies  of  the 
two  notes  to  each  other;  thus,  the  note  of  256  vibra- 
tions per  second  and  the  note  of  320  vibrations  per 
second  are  separated  by  the  same  interval  as  the 
notes  of  320  and  400,  the  interval,  namely,  of  4:5. 
The  intervals  separating  the  successive  notes  of 
the  diatonic  scale  (c,  d,  e,  f,  g,  a,  b,  c;  or  ut,  re, 
mi,  fa,  sol,  la,  si,  ut),  may  all  be  expressed  by  small 
fractions,  and  are  J,  T9o,  if,  f ,  T9o>  f >  tt-  The  rela- 
tive rates  of  vibration  of  the  notes  separated  by 
these  intervals  may,  therefore,  be  represented  by  the 
numbers  8,  9,  10,  lOf,  12,  13*,  15,  16.  The  rates 
of  vibration  of  the  harmonic  partials  (the  partials 
of  the  voice  and  of  musical  instruments  are  prac- 
tically harmonic)  are  1,  2,  3,  4,  5,  6,  7,  8,  and  so  on; 
the  second  vibrating  twice  as  fast  as  the  first,  the 
third  three  times,  the  fourth  four  times,  and  so  on.1 
It  is  evident  that  the  diatonic  scale  is  the  series  of 
harmonic  partials  from  the  eighth  to  the  sixteenth, 

1  The  harmonic  partials  are  those  whose  vibration-rates  are 
integral  multiples  of  the  rate  of  the  fundamental.  A  partial 
whose  rate  is  21,  times  that  of  the  fundamental  would  be 
classed  as  non-harmonic.  Tuning-forks,  bells,  and  metal 
plates  produce  non-harmonic  partials. 


I'HOTENSITY   AND   EXTENS1TY  129 

with    10§    substituted    for    11,    and    13J    for    13 
and  14. 

The  partials  up  to  the  ninth  are,  as  said  before, 
easily  produced  on  wind  instruments  (and  of  course 
on  stringed  instruments,  in  isolation,  by  stopping  the 
strings  as  described),  so  we  are  not  surprised  to  find 
that  in  the  earliest  scales  discoverable,  in  India, 
China,  and  the  British  Isles,  these  intervals  are  in- 
cluded. The  notes  employed  in  these  scales  are, 
as  represented  in  our  scale,  c,  d,  e,  g,  and  ajj ,  or  8, 
9,  10,  12,  13J.  Now  the  most  obvious  thing  about 
the  overtone  series  is  the  octave  relation,  1  :  2,  2  :  4, 
4  :  8,  etc.,  so  that  the  intervals  8  :  10  :  12  :  14  :  16 
are  equivalent  to  the  intervals  4:5:6:7:8;  and 
hence  all  the  intervals  of  the  primitive  scale  are 
really  given  by  the  overtone  series  up  to  nine,  ex- 
cept that  the  seventh  partial  is  replaced  by  a  slightly 
lower  note. 

The  modification  of  the  seventh  partial  is  the 
first  step  in  the  process  of  simplification  which  has 
given  us  the  modern  scale;  for  as  the  series  8:9: 
10  :  12  :  14  :  16  gives  no  two  intervals  alike,  the 
slight  flatting  of  14  to  13£  replacing  12  :  14  =  6  :  7 
by  12  :  13^  =  8  :  9,  or,  still  better,  flatting  to  13$ 
and  so  replacing  12  :  14  :  16  by  12  :  13$  :  16  = 
9  :  10  :  12,  thus  duplicating  intervals  already  in  the' 


130  A    SYSTEM   OF   PSYCHOLOGY 

scale,  simplifies  matters  much.  In  the  same  way, 
when  it  was  desired  to  insert  additional  notes  in  the 
larger  gaps,  the  notes  chosen  were  not  11  and  13, 
but  such  notes  as  would  introduce  the  fewest  new 
intervals;  and  these  would  be  the  notes  8  :  9  above 
13^  and  8  :  9  below  12,  i.  e.,  10§  and  15,  which  in- 
troduce only  one  new  interval,  10  :  10§  =  15  :  16.1 
The  scale  as  derived  contains,  therefore,  only  three 
different  successive  intervals;  8:9,  9  :  10,  and 
15  :  16;  the  major  tone,  minor  tone,  and  semitone. 
Having  derived  these  three  intervals,  the  ingenuity 
of  musicians  led  to  the  combination  of  the  inter- 
vals in  other  orders  to  fill  out  the  octave,  but  the 
one  which  came  nearest  to  the  overtone  series  is  the 
one  which  has  survived  in  use. 

A  still  further  development  has  displaced  the 
diatonic  scale,  which  is  practically  not  used  at  all 
now.  If  a  note  is  inserted  between  8  and  9,  15  :  10 
below  9;  and  another  15  :  10  above  8,  the  two 
notes  (8  i6  and  8  ^V)  are  separated  by  an  interval  of 
2025  :  2048.  The  pairs  of  notes  similarly  placed 
between  10§  and  .12,  and  13^  and  15  are  separated 
by  the  same  interval,  and  the  pairs  between  9  and 

1  The  interpolations  of  course  made  by  sound,  not  by  the 
abstract  ratio;  but  the  proper  sound  is  obtained  only  if  the 
physical  conditions  which  are  expressed  by  the  mathematical 
ratio  are  observed. 


PROTENSITY   AND   EXTENSITY  131 

10,  and  12  and  13 J  by  a  slightly  larger  interval.  In 
the  scale  derived  in  this  way — the  chromatic  scale — 
a(j  is  slightly  lower  than  gj},  and  so  on.  So  much 
for  the  amplification  of  the  scale;  now  for  the  sim- 
plification. The  chromatic  scale  is  absolutely  im- 
practicable except  for  a  few  gifted  musicians.  If 
a  single  note  standing  between  the  proximate  sharp 
and  flat  were  substituted  for  the  two,  the  resulting 
scale  of  twelve  notes  would  be  simpler,  but  too  irreg- 
ular. The  obvious  way  to  reduce  the  irregularities 
is  to  divide  the  octave  into  twelve  equal  parts,  doing 
away  at  one  stroke  with  the  distinction  between 
a$  and  bb,  etc.,  and  with  the  two  sorts  of  whole 
tones  (8  :  9  and  9:10)  and  the  two  sorts  of  major 
fifths.  Thus  we  have  a  scale  called  the  equally 
tempered  scale,  which  is  a  little  less  satisfactory  than 
the  chromatic  scale  in  some  respects,  but  immensely 
superior  in  other  ways.  The  equally  tempered 
scale  has  proved  so  superior  to  all  other  tempered 
scales  (other  scales  constructed  to  simplify  the 
chromatic  scale)  that  it  is  universally  adopted,  and 
all  modern  keyed  instruments  are  tuned  in  it — or, 
we  might  say,  tuned  to  it,  since  tuners  do  not  always 
succeed. 

The  Chinese  and  the  Hindus  achieved  a  twelve- 
fold division  of  the  octave,  as  did  probably   the 


132  A    SYSTEM   OF   PSYCHOLOGY 

Greeks  also.  Any  people  influenced  by  the  har- 
monic partials  and  alive  to  practical  musical  needs 
was  certain  to  hit  upon  some  sort  of  tempered  scale. 
The  Chinese  and  Hindus  went  still  farther,  and 
worked  out  subdivisions  smaller  than  the  twelfth  of 
the  octave,  but  seem  to  have  made  little  practical 
use  of  these  minutely  built  scales.  Savage  peoples, 
who  had  not  harmonic  instruments  (horns,  etc.)  and 
whose  music  was  produced  out-of-doors,  seem  to 
have  developed  scales  not  built  in  the  octave  at  all. 
This  statement  applies  to  some  North  African 
tribes,  at  least,  and  to  ancient  Egyptians  of  low 
caste.  Information  on  these  matters  is  for  the  most 
part  seriously  defective,  even  in  regard  to  existent 
tribes,  and  much  observation  has  been  rendered 
worthless  by  the  assumption  of  the  observer  that 
the  savages  are  attempting  to  use  intervals  repre- 
sented in  the  diatonic  scale,  and  that  their  devia- 
tions from  these  ideal  intervals  are  due  to  their 
clumsy  vocalization  and  inaccurate  "ear." 

4.  Timbre 

The  character  of  the  tones  of  different  instru- 
ments, or,  as  we  say,  their  timbre,  is  altogether  de- 
pendent on  the  presence  of  overtones  or  upper  par- 
tials.    The   particular  partials   present,   and   their 


PROTENSTTY    AND    EXTEXSITY 


1  oo 

[■)■} 


relative  intensities,  determine  the  voice  of  the  in- 
strument. 

The  partials  depend  on  the  faet  that  the  string, 
or  column  of  air,  or  other  vibrating  body,  is  vibrat- 


FiG.  9. 


Fig.   10. 


Fig.   11. 

Figures  9,  10,  and  11  are  intended  to  represent  schematically  the 
relations  of  fundamental  and  overtones  in  notes  of  the  organ-pipe, 
violin,  and  clarinet,  respectively.  The  pitch  is  represented  by  ttie 
length  from  left  to  right,  and  the  intensity  by  the  height  from  top 
to  bottom.  The  relative  intensities  of  the  partials  in  a  given  figure 
are  somewhere  near  those  actually  existing  in  the  characteristic  notes 
of  the  instrument.  In  the  representation  of  pitch  the  length  of  the 
partials  is  arbitrarily  made  inversely  proport  ional  to  the  vibration  rate. 
Notice  that  in  the  case  of  the  clarinet  (rig,  11)  the  second  partial  is 
missing,  while  the  third  partial  is  relatively  strong. 

ing  not  only  as  a  whole,  but  in  segments.  The  in- 
tensities of  these  segmental  vibrations  depend  on 
the  form  and  material  of  the  sonorous  body  and  the 
way  it  is  excited  or  set  in  motion.  The  voice  of  a 
violin,  for  example,  depends  in  large  measure  on 
the  condition   of  the  wood,   glue,  and   varnish   of 


134  A    SYSTEM   OF   PSYCHOLOGY 

which  it  is  made,  and  the  way  in  which  it  is  bowed. 
Pick  the  strings,  and  the  note  is  not  only  short  in 
duration,  but  has  a  characteristic  timbre  because 
the  relative  strengths  of  the  partials  are  not  the 
same  as  when  the  string  is  bowed.  The  difference 
between  the  tones  of  a  cylindrical  flute  and  a  clari- 
net is  partly  due  to  the  "bell"  on  the  end  of  the 
clarinet,  but  more  to  the  excitation  of  the  flute  by 
blowing  across  a  hole  and  of  the  clarinet  by  blow- 
ing through  a  reed.  The  note  of  the  trumpet  dif- 
fers from  that  of  the  cornet  because  of  the  differ- 
ent taper  of  its  bore. 

5.  Extensity  and  Intensity 

Extensities  are  comparable  in  the  way  in  which 
we  compare  intensities,  and  we  find  difficulty  in 
abstracting  the  extensity-differences  from  the  more 
complex  space-differences  just  as  we  find  in  the 
case  of  duration  and  time.  The  physical  measures 
of  just  perceptible  differences  are  found  to  increase 
with  the  extensities  compared,  but  apparently 
not  in  such  a  simple  way  as  is  formulated  for  in- 
tensities in  Weber's  Law.  In  pitch,  in  general, 
when  we  can  succeed  in  neglecting  the  metrical 
factor  of  scale  relationships,  differences  seem  equal 
when    the   corresponding   differences    in    vibration 


PROTENSITY   AND   EXTENSITY  135 

rate  are  equal.     This  may  mean  equal  differences 

in  number  of  nerve  endings  stimulated. 

Intensity  is  influenced  by  extensity,  and  vice 
versa.  It  is  well  known  that  a  small  spot  of  light 
falling  upon  the  retina  is  sensationally  not  so  bright 
as  a  larger  spot  of  the  same  physical  intensity  per 
unit  of  area.  A  weight  of  one  gram  resting  on  one 
square  centimeter  of  skin  feels  not  so  heavy  as  a 
weight  of  ten  grams  resting  on  ten  square  centi- 
meters. A  gustable  solution  applied  to  half  of  the 
tongue  is  productive  of  a  stronger  flavor  than  the 
same  solution  applied  to  a  smaller  area.  These 
effects  are  in  part  due  to  the  relatively  greater  ex- 
tent of  margin  of  a  small  area,  and  the  consequent 
greater  reduction  of  stimulus  energy  through  irradi- 
ation to  surrounding  areas,  but  there  may  be  other 
causes  at  work.  In  the  case  of  auditory  sensation, 
the  conditions  are  such  as  to  appear  at  first  the 
reverse  of  those  described  above;  a  high  note  of 
given  energy  sounding  more  intense  than  a  low  note 
of  same  energy.  This  is  doubtless  because  a  high 
note  affects  a  fewer  number  of  nerve  endings,  and 
hence  the  actual  stimulating  energy  is  greater  per 
unit  of  nerve  ending  than  in  the  case  of  the  lower 
note. 

Intensity  frequently  affects  extensity  through  the 


136  A    SYSTEM   OF   PSYCHOLOGY 

spreading  or  irradiation  just  mentioned.  The  ex- 
citation from  a  strong  stimulus  spreads  out  over  a 
larger  area  in  the  sense-organ  than  in  the  case  of  a 
weak  excitation.  This  is  readily  demonstrated  in 
vision  by  noting  the  apparent  increase  in  size  of  an 
electric  light  filament  as  it  begins  to  glow. 

The  reader  should  note  that  our  statement  that 
intensity  influences  extensity,  and  vice  versa,  is  meta- 
phorical, and  that  the  exact  statement  in  terms  of 
the  two  characters  and  the  corresponding  features 
of  the  stimulus  is  that  the  stimulation-conditions 
which  determine  the  extensity  and  the  intensity  of 
sensation  are  in  certain  cases,  at  least,  mutually  de- 
pendent. 


CHAPTER    VIII 

LOCAL  SIGNIFICANCE 
i.  Localization  and  Local  Sign 

Sensations  of  touch  and  temperature  on  any 
part  of  the  body  are  "localized"  more  or  less  cor- 
rectly; that  is,  are  felt  as  coming  from  the  locality 
of  actual  origin.  This  discrimination  must  be 
based  on  differences  in  the  sensations  from  the 
different  regions,  which  sensations  we  have  come  to 
be  able  to  refer  to  the  proper  places.  Suppose,  for 
instance,  your  eyes  are  closed,  and  some  one  noise- 
lessly touches  you  on  the  hand,  using  a  small  rod 
of  cork  to  obviate  temperature  sensations.  You 
can  decide  at  once  that  it  was  on  the  right  hand  and 
not  on  the  left;  which  is  sufficient  proof  that  the 
sensation  from  the  one  hand  is  different  from  the 
sensation  from  the  corresponding  point  of  the  other 
hand.  The  important  question  is:  What  are  the 
differences  which  serve  as  the  basis  of  this  local 
discrimination?  Differences  in  intensity,  exten- 
sity,  and  duration  can  be  ruled  out,  for  variations  in 

these  regards  do  not  influence  localization  except 

137 


138  A   SYSTEM  OF   PSYCHOLOGY 

in  extreme  eases.  Differences  in  quality  are  also 
excluded,  for  the  tactual  sensation  has  probably 
the  same  quality  everywhere  on  the  skin,  and  tem- 
perature sensations,  which  may  certainly  be  ob- 
tained in  different  regions  with  identical  quality, 
are  also  localized. 

The  fact  that  localization  does  not  depend  on 
quality  is  more  apparent  in  the  case  of  the  eye. 
Stimulations  of  different  points  of  the  retina  (if  not 
too  close  together)  are  always  discriminated  as  dif- 
ferent, and  by  habitual  association  referred  to  the 
relative  angular  positions  from  which  the  stimulat- 
ing rays  of  light  must  come.  The  discrimination 
of  positions  in  the  visual  field  depends,  in  short,  on 
the  discrimination  of  positions  on  the  retina.  And 
though  the  hue  of  a  color  roused  by  a  given  light 
stimulus  varies  according  to  the  part  of  the  retina 
stimulated,  there  are  many  different  points  in  the 
retina  giving  the  same  qualitative  mixture,  which 
are,  nevertheless,  discriminated.  The  hues,  more- 
over, may  be  varied  through  the  whole  range  of  the 
spectrum  without  affecting  the  locality  discrimina- 
tion; the  discrimination,  therefore,  cannot  depend 
on  quality. 

The  character  of  sensation  which  furnishes  the 
real  basis  for  localization  is  thus  demonstrable  only 


LOCAL   SIGNIFICANCE  139 

by  a  process  of  exclusion.  The  uniform  associa- 
tion of  this  character  with  the  space  position  of  the 
end-organ  prevents  our  separating  it  analytically 
from  this  spatial  factor,  but  since  the  character 
must  exist  as  a  basis  for  the  space  localization,  we 
give  it  the  name  of  local  significance,  or  particular- 
izing, local  sign.  Physiologically,  local  sign  proba- 
bly depends  on  the  individual  end-organs  which  are 
active,  but  nothing  more  can  be  said  at  present.1 

2.  The  Discrimination  of  Local-Sign  Differences 

In  order  that  a  difference  in  local  signs  may  be 
noticed,  it  must  have  a  certain  minimal  value, 
which,  however,  is  variable.  Similar  points  on  the 
corresponding  fingers  of  the  two  hands  can  nor- 
mally be  distinguished,  but  if  the  hands  are  kept 
behind  a  screen  for  some  time,  and  the  fingers  not 
stimulated,  the  patient  tends  to  become  uncertain 
as  to  which  hand  is  touched.     The  signs  apparently 

1  There  is  a  theory  that  local  signs  are  muscular  sensation 
accompanying  the  primary  sensation,  or  are  the  images  of 
muscular  sensation  arising  from  the  past  experience  of  the 
muscular  action  necessary  to  bring  the  hand,  or  other  mem- 
ber, to  the  spot  on  the  skin  with  which  the  sign  is  connected. 
This  theory  is  rather  a  work  of  supererogation,  because  it 
must  assume  a  local  sign  of  the  sensation  in  order  that  it  may 
rouse  the  proper  muscular  images;  in  other  words,  the  theory 
does  not  touch  the  problem  of  local  significance  at  all.  That 
muscular  sensation  has  a  great  deal  to  do  in  the  discrimination 
and  systematization  of  local  signs  is  another  matter. 


140  A    SYSTEM   OF   PSYCHOLOGY 

are  so  nearly  alike  that  the  person  forgets  which  is 
which  unless  he  has  a  chance  to  freshen  his  memory 
from  time  to  time.  In  general,  the  closer  two  points 
are  on  the  skin,  the  nearer  alike  are  the  local  signs 
of  the  sensations  aroused  therefrom;  consequently, 
on  any  part  of  the  body  there  is  a  certain  minimal 
distance  by  which  two  simultaneously  applied  com- 
pass points  must  be  separated,  if  they  are  to  be  felt 
as  two.  If  the  distance  between  the  two  compass 
points  is  less  than  the  minimum,  the  two  points  are 
felt  as  one,  because  the  difference  in  local  signs  is 
not  enough  for  discrimination,  although  the  two 
may  be  felt  as  "bigger"  than  either  alone,  probably 
because  more  nerve  endings  are  stimulated  in  the 
former  case. 

The  minimal  distance  of  separation  of  two  stim- 
ulating points  felt  as  two  is  commonly  known  as 
the  "  two-point  threshold,  and  the  determination  of 
this  threshold  is  called  "sesthesiometry."  1 

1  Several  explanations  have  been  proposed  for  the  physio- 
logical side  of  the  two-point  threshold,  but  so  far  it  remains 
principally  a  matter  for  theory.  A  probable  theory  is  based 
on  the  fact  that  all  dermal  nerve  endings  are  connected  with 
deeper-lying  nervous  structures,  and  that  the  endings  con- 
nected with  one  deeper  organ  are  interspersed  in  the  skin 
with  endings  connected  with  other  of  the  deeper  structures. 
Any  touch  stimulus,  therefore,  is  apt  to  affect  two  or  more  of 
the  deeper  organs,  and  if  we  assume  that  the  local  sign  is 
associated  with  the  deeper  structure  rather  than  with  the 
dermal  ending,  it  follows  that  a  touch  gives  a  combination  of 


LOCAL   SIGNIFICANCE  141 

In  order  that  practice  may  influence  the  local- 
ization of  sensation,  and  in  order  that  differences  in 
local  sign  may  be  discriminated  at  all,  it  is  neces- 
sary that  the  signs  to  be  discriminated  shall  at  some 
time  occur  in  independence  of  each  other.  If  two 
signs  or  groups  of  signs  are  habitually  aroused  to- 
gether, it  is  difficult  to  discriminate  them;  if  they 
are  invariably  aroused  together,  discrimination  is 
impossible.  Touches  on  the  opposite  edges  of  two 
adjacent  fingers  are  easily  discriminated;  touches 
on  the  apposed  edges  are  not  discriminated  so  read- 
ily, especially  if  near  the  palm;  and  if  two  nor- 
mally apposed  spots  are  simultaneously  stimulated, 
the  experience  is  apparently  of  a  single  touch.  This 
last  phenomenon  results  from  the  fact  that  the 
apposed  areas  are  usually  stimulated  by  a  single 
object. 

In  the  case  of  the  eyes,  the  necessity  of  indepen- 

sensations  of  different  local  signs.  The  relative  intensity 
of  the  sensations  in  a  given  sensation-combination  is  accord- 
ingly the  datum  for  the  minute  localization  of  the  mass.  This 
theory  is  supported  by  the  fact  that  practice  greatly  reduces 
the  two-point  threshold,  and  by  the  fact  that  in  many  cases 
a  single  touch  is  perceived  as  two  or  even  three. 

The  threshold  varies  from  one  millimeter  or  less  on  the  tip 
of  the  tongue  and  the  finger-tips,  to  several  centimeters  on 
the  middle  of  the  back.  It  bears  no  definite  relation  to  the 
intensity-threshold,  or  to  the  intensity  difference  threshold 
on  the  different  parts  of  the  body.  It  is  smaller  on  the  more 
motile  portions  of  the  body. 


142  A    SYSTEM   OF   PSYCHOLOGY 

dent  stimulation  is  strikingly  made  evident.  Nor- 
mally, when  any  point  in  one  eye  is  stimulated,  a 
definite  corresponding  point  in  the  other  eye  is  stimu- 
lated in  practically  the  same  way.  Hence,  if  under 
experimental  conditions  one  eye  alone  is  stimulated 
by  light,  the  person  is  unable  to  tell,  from  that 
stimulation  alone,  which  eye  is  affected.1  This 
peculiarity  of  vision  is  of  practical  importance,  for 
the  stimulation  of  corresponding  points  in  the  two 
eyes  produces  single  vision ;  that  is  to  say,  if  two  im- 
ages nearly  identical  in  form  and  detail,  are  thrown 
on  corresponding  portions  of  the  retina?,  a  single  ob- 
ject is  seen,  whether  the  two  images  come  from  a 
single  "  real "  object  or  from  a  stereoscopic  picture. 
On  the  other  hand,  if  the  images  of  an  object  fall  on 
portions  of  the  retinae  not  corresponding,  the  object 
is  "seen  double."  This  effect  is  easily  produced 
by  crossing  or  "walling"  the  eyes,  or  by  pushing 
on  the  ball  of  one  eye  with  the  tip  of  the  finger  (on 

1  This  may  be  demonstrated  in  a  dark  room.  Let  the  per- 
son gaze  at  a  feeble  light,  as  a  pinhole  gas  flame,  or  phos- 
phorescent spot,  having  both  eyes  open  and  his  head  fixed  in 
position.  You  may  bring  a  card  in  front  of  one  of  his  eyes, 
and  he  will  be  unable  to  tell  which  eye  is  seeing.  The  light, 
if  a  gas  flame  is  used,  must  be  so  dim  that  he  cannot  see  the 
card  itself,  and  he  must  refrain  from  winking.  Another 
demonstration  may  be  made  with  a  pair  of  spectacles,  one 
lens  plain  and  the  other  slightly  prismatic.  The  person  will 
not  know  which  image  is  displaced. 


LOCAL   SIGNIFICANCE  14o 

the  lid,  of  course),  or  by  bringing  a  prism  before 
one  eye. 

Corresponding  points,  as  the  term  is  used  in 
psychology,  may  be  defined  as  points  on  the  two 
retinae  which  are  normally  stimulated  by  rays  of 
light  from  a  single  point  in  an  object  upon  which 
the  eyes  converge.  Corresponding  areas  of  the 
retime  are,  accordingly,  areas  which  correspond 
point  for  point. 

3.  Local  Sign  In  Auditory  Sensation 

It  is  possible  that  local  sign  plays  an  important 
part  in  auditory  sensation.  According  to  the  Helm- 
holtz  theory,  pitch  really  reduces  to  local  sign.  If 
each  rate  of  audible  vibration  should  stimulate  a 
small  group  of  hair  cells  on  the  basilar  membrane, 
each  corresponding  sensation  would  have  a  specific 
local  sign,  and  these,  differing  from  one  another  in 
accordance  with  the  separation  of  the  hair  cells 
in  the  series,  would  form  a  linear  series.  The  sen- 
sations would  not  be  localized,  there  being  no  mus- 
cular mechanisms  to  assist  in  the  associative  proc- 
ess; so  the  series  of  pitches  would  remain  a  series 
of  practically  pure  local  signs. 

Assuming  that  the  Helmholtz  theory  is  not  cor- 
rect, and  that  pitch  is  primarily  cxtensity  of  audi- 


144  A   SYSTEM   OF   PSYCHOLOGY 

tory  sensation,  local  signs  may  still  be  important 
in  connection  with  tones.  Each  pitch  may  come 
to  be  associated  with  a  certain  local  sign,  namely, 
that  of  the  group  of  end-organs  at  which  the  excita- 
tion on  the  basilar  membrane  ends.  Thus,  the 
series  of  local  signs  becomes  the  series  of  symbols 
of  the  extensities  primarily  constituting  pitches. 
Extensity  itself  can  be  estimated  only  approxi- 
mately by  direct  observation;  this  is  true  in  both 
visual  and  tactual  estimation,  and  it  is  possible  that 
the  person  of  "uneducated  ear"  distinguishes  pitch- 
differences  crudely  because  he  attempts  to  judge  in 
this  way.  The  person  of  "musical  ear,"  on  the 
other  hand,  has  possibly  acquired  the  ability  to 
notice  the  local  signs,  which  lend  themselves  to 
more  accurate  identification,  and  has  formed  an 
accurate  system  of  associations  between  these  local 
signs  and  the  marks  of  musical  notation.  Nothing 
is  more  certain  than  that  musical  and  non-musical 
people  employ  different  methods  of  estimation  of 
pitch,  and  that  the  cultivation  of  the  "ear"  is  a 
process  of  learning  how  to  observe. 

The  immediately  foregoing  remarks  do  not  apply 
to  cases  of  organic  defect  in  the  auditory  appa- 
ratus. There  are  persons  who  can  never  learn  to 
distinguish  pitches  accurately;    some  peculiarity  of 


LOCAL  SIGNIFICANCE  145 

their  aural  mechanism  doubtless  prevents  the  ex- 
citations from  being  sharply  defined,  a  condition 
which  may  properly  be  designated  amblacousia. 

4.  Olfactory  Local  Sign 

Local  sign  may  have  something  to  do  with  the 
baffling  composition  of  odors.  Some  of  the  peculiar 
similarities,  and  differences  of  smell  sensation  may 
really  be  identities  and  differences  of  local  sign. 
We  must  remember  that  we  never  experience  the 
local  sign  of  dermal  or  visual  sensation  without  its 
associative  connection  with  space,  nor  local  sign 
of  auditory  sensation  apart  from  the  corresponding 
extensity;  hence,  local  sign  unassociated  with  either 
of  these  factors,  or  associated  with  extensity  in  a 
non-serial  way,  would  not  be  naively  identified. 


CHAPTER   IX 

RELATIONAL    ELEMENTS    IN    THE    CONTENT    OF 
CONSCIOUSNESS 

i.  General 

In  discussing  sensations  we  have  necessarily  dis- 
cussed the  relations  in  which  they  are  experienced, 
but  with  reference  always  to  the  sensations.  Now 
we  must  focus  our  attention  on  the  relations  them- 
selves, and  consider  them  in  their  turn  as  elements 
of  content. 

Just  as  you  directly  perceive  sensations,  so  you 
perceive  relations.  This  red  is  perceived  as  differ- 
ent from  green;  as  like  that  other  red;  as  brighter 
than  this  one;  as  lying  on  the  table;  as  more  beau- 
tiful than  this  dingy  color;  and  so  on.  But  it  is 
not  only  sensations  that  are  involved  in  complexes 
of  relations;  emotional  content  (assuming  for  the 
present  that  it  is  a  specific  content)  is  equally  in- 
volved with  the  relational  factors. 

In  the  treatment  of  relation  we  encounter  much 

more  difficulty  than  in  the  treatment  of  sensation, 

146 


RELATIONAL   ELEMENTS  147 

because  of  the  way  in  which  relations  complicate 
themselves  in  groups  which  seem  like  single  rela- 
tions; and  also  because  of  the  elaborate  processes 
through  which  we  learn  to  perceive  certain  of  these 
systems.  We  can  develop  in  this  chapter  only  the 
general  line  of  analysis  to  which  this  content  must 
be  submitted,  and  amplify  only  enough  for  the  pur- 
poses of  the  other  portions  of  our  work  which  come 
into  close  connection  herewith. 

The  most  conspicuous  peculiarity  of  relation- 
content  is  that  it  has  no  definitely  assignable  ner- 
vous process  corresponding  to  it.  We  know  of  no 
"centre"  in  the  brain  for  the  perception  of  relations, 
and  we  do  not  know  that  it  is  a  cortical  function  at 
all.  We  must  not  suppose  that  perceived  relations 
depend  on,  or  are  functions  of  "  brain-paths,"  or 
"association  fibres;"  brain-paths  represent  simply 
connections  established  between  different  factors 
of  content,  by  the  operation  of  which  the  factors 
function  together;  the  physiological  connection  is 
not  the  same  thing  as  the  experienced  connection 
or  relation,  and  the  physiological  connection  may 
function  perfectly  whether  a  specific  relation  is 
experienced  or  not.  It  is  true  that  there  are  a 
number  of  motor  processes  which  assist  in  the  per- 
ception of  relation,  but  their  neural  consequences 


148  A    SYSTEM   OF   PSYCHOLOGY 

are  no  more  to  be  considered  as  the  counterparts 
of  the  experienced  relations  than  the  neural  excita- 
tion caused  by  the  movements  of  the  eye  are  to  be 
considered  as  the  counterpart  of  the  color  sensa- 
tion, in  the  obtaining  of  which  the  eye-movements 
assist.  These  points  will  become  clearer  as  we 
proceed  to  the  analysis  of  complex  perceptions. 
For  the  present  we  may  repeat,  that  while  we  in- 
cline to  believe  that  there  are  specific  brain  proc- 
esses corresponding  to  the  relational  content  of 
consciousness,  as  there  are  to  sensational  content, 
the  belief  is  as  yet  merely  a  detail  of  the  general 
a  priori  theory  of  the  relation  of  nervous  process 
to  experience. 

The  enumeration  of  elementary  relations  or 
groups  of  elementary  relations  is  a  difficult,  not  to 
say  impossible,  procedure  in  the  present  stage  of 
psychological  analysis.  The  greater  number  of 
familiar  relations  are  doubtless  complex.  The  rela- 
tions of  causality,  of  inadequacy,  of  up  and  down, 
and  so  on,  are  really  involutions  of  a  number  of 
relations  whose  final  analysis  is,  perhaps,  not  yet 
to  be  made.  To  particularize:  the  relation  which 
we  call  causality  involves  the  relation  of  succession 
— or,  perhaps,  simultaneity — the  relation  of  in- 
variability, and,  according  to  one  view,  the  complex 


RELATIONAL   ELEMENTS  149 

of  relations  involved  in  the  "  transfer  of  energy."  x 
Take  now  the  factor  of  succession;  is  it  a  simple 
relation?  Probably  not.  It  involves  the  relations 
of  betweenness  and  difference,  with  a  certain  re- 
semblance, and  the  peculiar  relation  to  other  phe- 
nomena involved  in  time. 

As  examples  of  relations  which  are  probably 
elementary  we  may  name  the  following:  difference, 
identity,  similarity,  greater,  less,  betweenness,  direc- 
tion (peculiar  to  space),  a  relation  peculiar  to  time, 
agreement,  and  possibly  the  relations  of  good  and 
bad.  At  any  rate,  it  is  difficult  to  see  how  these  can 
be  resolved  into  any  other  relations:  but  the  list 
is  only  a  suggestion. 

2.  Platonic  Ideas  and  Matter 

The  importance  of  relations  in  the  content  of 
consciousness,  and  in  the  supposed  world  lying 
behind  experience,  has  always  been  recognized,  and 
perhaps  rather  overestimated  than  underestimated. 
The  "  Ideas"  of  the  Platonic  philosophy  are  nothing 
less  than  systems  of  relations;  at  least  this  phi- 
losophy  is   pretty  good   common-sense  when   the 


1  Of  course,  these  relations  are  not  perceived  in  this  combina- 
tion; that  is  to  say,  we  never  perceive  causation  outright,  but 
perceive  a  part  and  imagine  the  rest. 


150  A    SYSTEM   OF   PSYCHOLOGY 

"Ideas"  are  so  interpreted.  The  philosophy 
called  "  Idealism"  always  emphasizes  the  relations 
in  the  content,  making  them  the  prime  or  essential 
part,  and  the  sensory  factor  trivial  or  secondary. 
Surprising  as  it  may  seem,  the  apparently  opposed 
theory  of  "Materialism"  has  simply  abstracted 
some  of  the  most  universal  and  characteristic  re- 
lations from  the  content  of  consciousness  and  given 
them  the  names  of  "Matter"  or  "Substance."  So, 
from  the  psychological  point  of  view,  these  two 
systems  are  more  nearly  identical  than  opposite. 
Empiricism,  which  we  believe  to  be  a  more  adequate 
view,  recognizes  the  importance  of  relational  and 
non-relational  content,  and  does  not  attempt  to  set 
either  above  the  other. 

3.  Intellect 

The  perception  of  relation  is  commonly  called 
intellect,  in  both  scientific  and  popular  discourse. 
In  common  language  we  speak  of  a  man  as  being 
"intellectual"  in  so  far  as  he  is  quick,  accurate,  or 
thorough  in  the  noticing  of  relations;  without  re- 
gard to  his  keenness  of  sense  perception,  or  his  emo- 
tional capacity,  or  his  will.  Of  course  these  fac- 
tors of  his  total  experience  are  never  sundered,  and 
each  is  important  for  the  others,  but  high  develop- 


RELATIONAL   ELEMENTS  151 

ment  of  one  does  not  imply  development  of  the 
others  to  the  same  degree. 

4.  The  Reality  of  Relational  Content 

There  are  several  theories  of  relation-content 
which  attempt  to  explain  it  away.  The  so-called 
"sensationalist"  theory  supposes  the  relation  to  be 
a  sort  of  fusion  or  combination  of  the  sensations. 
The  "motor"  theory  supposes  that  our  reactions 
to  the  sensory  content  constitute  both  the  relations 
of  the  content  within  itself  and  to  other  content. 
While  we  do  not  wish  to  underestimate  the  im- 
portance of  these  theories,  we  wish  to  point  out  that, 
psychologically,  they  are  only  statements  of  the 
conditions  and  consequences  of  the  experience  of 
relations,  and  not  explanations  of  the  experienced 
relations  themselves.  The  fact  remains  that  re- 
lations are  really  perceived,  and  the  attempt  to 
evade  this  by  substituting  for  the  relation  a  fusion 
of  sensations  or  a  motor  process  is  a  waste  of  energy. 
The  relation  is  as  much  a  reality  as  the  factors  it 
relates,  and  we  perceive  it  just  as  truly  as  we  per- 
ceive them. 

We  cannot  deal  adequately  with  relation  in  ab- 
straction from  the  other  forms  of  content  without 
getting  outside  of  the  field  of  psychology.     Two 


152  A   SYSTEM   OF   PSYCHOLOGY 

sciences — or  two  branches  of  the  same  science,  if 
you  choose — deal  specifically  with  relations:  these 
two  are  logic  and  mathematics,  and  the  serious 
student  of  psychology  is  advised  to  make  himself 
well  acquainted  with  both  of  them,  not  for  their 
specific  methods  or  results,  but  for  their  points  of 
view. 


CHAPTER  X 

IMAGES  AS   ELEMENTS   OF   CONTENT 
I.  Imagination  and  "  Image-Types  " 

We  have  already  referred  to  the  prevalent  doc- 
trine of  images  as  copies  of  sensations,  or  copies  of 
sensation-complexes.  This  doctrine  is  older  than 
Aristotle,  who  stated  it  pretty  clearly,  and  who, 
perhaps,  gave  it  its  definite  formulation;  and  it 
has  been  incorporated  in  some  form  in  practically 
every  general  theory  of  psychology  since  his  time. 
In  modern  times  impetus  has  been  given  to  the  the- 
ory by  the  introspective  and  experimental  work  of 
Fechner  and  Galton,  in  whose  steps  many  psy- 
chologists have  followed. 

Galton    alleged    that    there    are — or    may    be — 

images    of   different    senses,    but    that    images    of 

vision  and  audition  are  the  most  important  in  the 

consciousness  of  adults.    Galton  compiled  a  "  ques- 

tionary"  which  was  sent  to,  and  answered  by,  a 

great   many    persons    of   all    sorts;    the    object    of 

the  questionary  being  to  determine  the  kinds  and 

153 


154  A    SYSTEM   OF   PSYCHOLOGY 

relative  clearness  of  the  images  possessed  by  these 
persons.1 

Imagination  as  an  actual  process  or  function 
cannot  be  denied,  nor  is  there  any  doubt  that  when 
you  imagine  certain  objects  they  will  have  a  visual, 
or  auditory,  or  other  sensory  reference.  Some  psy- 
chologists have  denied  the  existence  of  images  of 
taste  and  smell;  indicating  thereby  a  personal 
peculiarity,  for  the  olfactory  and  gustatory  features 
of  imagination  are  for  some  persons  the  most  vivid. 

Muscular  imagination  has  received  due  credit 
in  the  various  attempts  at  analysis,  and  it  has  been 
stated  with  apparent  justification  that  much  of  our 
"  thinking,"  or  trains  of  representation,  goes  on 
through  the  activity  of  the  "images"  of  spoken 
words,  and  that  these  "images"  are  usually  mus- 
cular, i.  c,  representations  or  reproductions  of  the 
muscular  sensations  which  occur  in  speaking  the 
words.  In  reality,  the  alleged  muscular  images 
may  be  muscular  sensations.     (See  below.) 

In  accordance  with  the  accepted  view,  individu- 
als are  classified  under  "types"  corresponding  to 
the  sorts  of  "images"  they  employ  most  constantly 

1  The  intention  of  the  questionary  and  Galton's  views  on  the 
subject  of  images  are  best  obtained  from  his  Inquiries  into 
Human  Faculty.  The  gist  may  be  found  in  James,  Principles 
of  Psychology,  II,  51-57. 


IMAGES   AS   ELEMENTS   OF   CONTENT        155 

and  readily.  The  predominance  of  images  of  the 
muscular  sensations  marks  one  as  of  the  "motor 
type,"  and  the  predominance  of  images  of  the  audi- 
tory or  visual  sensory  sorts  marks  one  as  of  the 
"  auditory  type,"  or  the  "  visual  type."  A  person  of 
either  motor  or  non-motor  type  may  be  of  the  "verbal 
type,"  i.  e.,  may  employ  "images"  of  heard  or  seen 
or  spoken  words.  The  terminological  development 
has  been  carried  still  farther,  but  we  need  not  pur- 
sue it  beyond  this  point.1 

When  we  come  to  the  actual  determination  of 
"types"  in  accordance  with  the  Aristotelian  theory 
of  "images,"  the  trouble  begins.  Determination 
by  the  simple  introspection  upon  which  the  ques- 
tionaries  depend  is  usually  unsatisfactory  to  the 
patient,  and  still  more  so  to  the  persons  conducting 
the  investigation.  Several  auxiliary  tests  have  been 
devised,  but  they  all  depend  on  the  interpretation 
of  the  results  by  assumptions  which  beg  the  whole 
question. 

As  regards  the  physiological  processes  causing 
or  corresponding  to  imagination,  the  most  natural 
theory  based  on  the  Aristotelian  view  is  that  the 

1  A  person  of  the  auditory  type  is  sometimes  called  an 
"audile";  of  the  visual  type  a  "visile."  "Tactile,"  "olfactile" 
and  "gustile"  have  been  used  also,  hut  are  not  in  such  high 
repute.     "Motile"  is  in  good  usage. 


156  A   SYSTEM  OF  PSYCHOLOGY 

imagination  process  (production  of  the  "image,") 
is  simply  a  revival  of  the  sensation  process  in  a 
weaker  form.  The  imagination-centres  are,  ac- 
cordingly, supposed  to  be  identical  with  the  sensory 
centres,  and  the  determinative  difference  between 
the  imagination  process  and  the  sensation  process 
is  considered  to  be  due  to  the  initiation  of  the  latter 
from  the  sense-organ,  and  of  the  former  from  some 
other  brain-centre;  the  currents  from  the  periph- 
eral organs  being  supposed  to  be  more  powerful 
than  the  intra-cerebral  discharges.  This  theory 
of  the  brain  process  on  which  imagination  depends 
was  quite  widely  held  a  decade  or  two  ago,  but  it 
is  now  believed  that  the  imagination  process  de- 
pends on  a  portion  of  the  cerebrum  contiguous  to, 
or  bordering  on,  the  sensory  area  of  the  cortex. 

We  ought  not  to  consider  an  "image"  as  a  spe- 
cific content,  or  a  specific  form  of  content,  until  we 
have  more  proof  of  the  existence  of  that  sort  of  an 
"image."  Revived  or  false  sensations  probably 
do  occur  (the  "subjective"  sensations  of  the  physi- 
ologist) but  they  are  not  what  is  meant  by  "image" 
or  imagination.  Actual  normal  sensations  from  the 
various  organs  may  assist  us  in  representation  or 
thinking,  but  they  are  not  a  new  form  of  content 
on   that  account.     Imagination   is  a   fact  of  con- 


IMAGES  AS  ELEMENTS  OF  CONTENT   157 

sciousness;  it  is  a  way  of  being  conscious  of  content 
of  various  sorts,  and  not  a  specific  content,  so  far 
as  we  are  able  to  determine.1 

The  specific  sensory  reference  in  imagination, 
which  is  the  basis  of  the  Aristotelian  theory,  is 
imparted  in  several  ways,  two  at  least  of  which  we 
may  point  out.  The  sensory  tang  may  be  given 
because  the  object  of  which  we  are  thinking  was  an 
object  for  the  sense  in  question  when  experienced 
directly.  The  visible  features  of  an  object  may  be 
the  important  characteristics  for  one  man,  and  to 
these  principally  he  attends.  Another  man  may 
attend  principally  to  the  sound  made  by  the  ob- 
ject. In  recalling,  or  thinking,  of  the  object,  the 
first  man  will  recall  it  as  a  visible  object,  and  the 
second  as  an  auditory  object;  each  will  think  of  it 
as  it  impressed  him.  But  it  is  an  unsafe  leap  from 
this  bald  and  unexplained  fact  to  the  assumption 
that  the  first  man  has  a  "copy"  of  the  visual  sensa- 
tions and  the  second  a  "copy"  of  the  auditory  sen- 
sations. 

In  some  cases  the  mechanism  by  which  the  sen- 
sory mark  is  given  is  assignable.     When  sensations 


1  It  is  convenient  to  use  the  term  "image"  to  designate  the 
represented  content,  and  we  shall  do  so,  in  spite  of  our  dis- 
sent from  the  general  belief  as  to  its  nature. 


158  A    SYSTEM   OF   PSYCHOLOGY 

from  a  definite  sense,  or  sensations  which  are  the 
normal  concomitant  of  that  sense,  occur  along  with 
imagination,  they  tend  to  give  the  imagination  the 
corresponding  tang.  This  may  be  the  means  by 
which  the  influence  of  the  preceding  direction  of 
attention  to  the  object  is  realized,  or  it  may  be  in 
some  cases  the  agency  which  counteracts  such  in- 
fluence. The  sensations  in  question  may  be  from 
the  sense  to  which  the  imagination  is  ascribed; 
faint  sensations  from  the  retina,  I.  e.,  of  light,  may 
give  the  visual  reference  to  the  "image";  but 
usually  the  sensations  are  from  the  motor  apparatus 
functionally  connected  with  the  sense-organ. 

In  thinking  of  a  visual  object,  c.  g.,  of  an  illumi- 
nated sign,  there  are  movements  of  accommodation 
and  convergence  of  the  eyes,  if  the  person  is  of  the 
"visual"  type.  In  thinking  of  the  sound  of  an 
orchestra  there  are  changes  in  tension  of  the  mus- 
cles in  the  tympanum  of  the  ear,  or  in  the  neck- 
muscles.  If  you  fix  your  eyes  on  a  point  on  the  wall 
you  will  probably  find  it  difficult  to  call  up  the  pict- 
ure of  a  ship  under  sail;  let  the  eyes  wander  freely 
and  the  picture  comes  up  readily.  Fixate  steadily 
a  square  of  mosquito  netting,  and  the  picture  will 
probably  not  come  at  all;  this  is  because  the  net- 
ting offers  an  excellent  object  for  steady  fixation. 


IMAGES   AS   ELEMENTS   OF   CONTENT        159 

Some  persons  find  a  great  decrease  in  facility  of 
visual  imagination  when  the  eyes  are  under  the  in- 
fluence of  atropine;  in  the  case  of  these  persons  the 
sensations  of  accommodation  are  important  in  mark- 
ing the  image. 

If  you  can  readily  recall  or  imagine  odors  try  the 
following  experiment:  take  a  deep  breath,  and  have 
some  one  else  name  an  odor  just  as  you  begin  to 
exhale  slowly  through  the  nose;  you  will  find  that 
you  do  not  get  the  image  until  you  begin  to  inhale, 
and  probably  not  then  if  the  inhalation  is  slow. 
Sniff,  and  the  image  appears  at  once.  Certain 
persons,  whose  taste  images  are  extremely  vivid, 
cannot  get  them  unless  the  tongue  is  allowed  to 
move. 

A  type  of  experiment  which  is  noteworthy  may 
be  exemplified  in  the  following  way:  put  the  vocal 
organs  in  position  to  say  "Ah,"  and,  holding  them 
so,  try  to  think  or  image  the  word  "soap-bubble," 
or  "  parsimonious."  The  word  will,  in  most  cases, 
not  "  think"  fluently.  Such  results  have  been  held 
to  demonstrate  that  the  images  of  the  words  are 
"motor."  It  really  shows  only  the  close  connec- 
tion between  the  muscular  sensations  from  the  vocal 
organs  and  the  imagining  of  the  words. 

The  very  ease  with  which  individuals  have  been 


160  A    SYSTEM   OF   PSYCHOLOGY 

convinced  that  what  they  before  believed  to  be 
"visual"  or  "auditory"  images  were  really  "mus- 
cular," as  a  result  of  experiments  like  the  one  just 
described,  is  in  itself  sufficient  to  raise  a  serious 
presumption  against  the  Aristotelian  theory.  Like- 
wise, the  maintenance  by  certain  persons,  among 
whom  are  trained  psychologists,  that  they  never 
have  any  images  such  as  Galton  and  others  describe, 
is  a  significant  circumstance.  If  the  sensory  ref- 
erence is  not  intrinsic,  but  dependent  on  the  me- 
chanical interpretation  of  attendant  sensations,  these 
anomalies  are  quite  explicable. 

2.  The  Function  of  Imagination 

Although  the  discussion  of  imagination  belongs 
logically  to  the  later  chapters  of  this  book,  we  must 
anticipate  somewhat,  in  order  to  describe  the  be- 
havior of  the  content  when  apprehended  imagina- 
tively, and  the  way  in  which  that  behavior  modifies 
the  total  content  in  perception. 

We  are  naively  disposed  to  think  of  imagination 
as  a  play  of  fancy  which  may  be  amusing  and  in- 
teresting, but  hardly  as  subserving  the  more  prac- 
tical and  prosaic  processes  of  thought.  As  a  mat- 
ter of  fact,  this  latter  is  just  what  imagination  does. 
Imagination  is  the  basis  of  memory  and  of  all  rea- 


IMAGES   AS   ELEMENTS   OF   CONTENT        161 

soning  processes,  and  upon  it  depends  the  percep- 
tion of  objects  in  the  world  about  us. 

Whatever  has  been  perceived  may  be  imagined 
in  much  the  same  form.  Having  seen  a  lion  and 
heard  it  roar,  I  may  on  some  subsequent  occasion 
imagine  a  lion  of  the  same  appearance,  and  with 
the  same  sort  of  a  roar.  The  content  is  indeed 
never  exactly  the  same  in  imagination  as  it  was  in 
perception,  but  the  difference  may  be  unimportant. 
This  approximate  repetition  of  a  former  content  is 
the  reproductive  function  of  imagination,  and  we 
speak  of  it  simply  as  reproductive  imagination. 
According  to  the  Aristotelian  theory  the  content 
is  an  approximate  copy  of  a  former  sense-con- 
tent. 

On  the  other  hand,  content  may  be  imagined  in 
forms  and  combinations  quite  different  from  those 
of  the  original  perception,  and  hence  we  are  able 
to  imagine  things  which,  strictly  speaking,  we  have 
never  perceived.  Sensory  content  experienced  in 
one  perception  may  creep  in  with  content  of  another, 
or  certain  sensory  factors  may  be  eliminated  from  a 
former  content.  New  relations  may  be  introduced, 
and  old  relations  modified.  In  consequence  of 
these  changes  we  have  not  only  a  general  modifica- 
tion by  which  the  content  of  all  experience  tends  to 


162  A    SYSTEM   OF   PSYCHOLOGY 

lose  its  individuality,  but  also  the  special  case  which 
we  call  creative  imagination. 

One  who  imagines  a  perfectly  "impossible" 
animal,  a  griffin  or  a  "goop",  is  imagining  a  con- 
tent composed  or  built  up  of  the  elements  of  a  mass 
of  content  which  he  has  previously  perceived.  It 
is  only  necessary  to  modify  the  human  figure  by 
changing  certain  contours  in  ways  which  are  al- 
ready familiar,  and  the  "goop"  is  invented.  Any 
one  of  us  could  imagine  all  the  details  separately, 
or  in  other  combinations;  otherwise  we  should  not 
appreciate  the  "goop;"  the  notable  feat  was  in 
imagining  them  combined.  In  poetry,  the  content 
suggested  is  such  as  we  can  all  imagine — if  the 
poetry  appeals  to  us — but  the  poet  has  combined 
it  in  new  ways.  The  scientist,  in  discovering  a 
new  principle,  is  able  to  imagine  what  he  has  never 
perceived,  by  imagining  old  content  in  new  combina- 
tions; then,  if  his  imagining  has  been  successful, 
he  is  able  to  use  new  methods  or  arrange  new  con- 
ditions of  experiment,  so  that  what  he  imagined  be- 
comes now  perceived,  or  he  is  able  to  demonstrate 
his  results  logically. 

In  creative  imagination  the  creator  is  aware  of 
the  modification  of  the  content.  Along  with  the 
rest  of  the  content  he  has  the  peculiar  factor  which 


IMAGES   AS   ELEMENTS   OF   CONTENT        1G3 

we  call  newness,  or  novelty.  He  is  aware  that  his 
content  is  a  new  combination.  But  in  the  general 
modification  of  content  which  we  mentioned  above, 
the  person  is  less  apt  to  be  aware  of  the  changes. 
The  fisherman  who  magnifies  into  a  three-pounder 
the  minnow  which  escaped;  the  student  who  re- 
lates the  hard-luck  story  of  how  he  "failed"  in  an 
examination  through  no  fault  of  his  scholarship; 
are  in  many  cases  quite  sincere,  and  base  their  tales 
on  imagined  content  which  has  undergone  progres- 
sive "improvement"  since  it  was  experienced  in 
perception. 

A  distinction  has  frequently  been  made  in  the  past 
between  the  image  and  the  idea.  The  image  was 
supposed  to  be  the  special  content  in  imagination, 
and  the  idea  to  be  that  to  which  the  image  referred, 
or  which  it  meant;  or  else  the  idea  was  supposed 
to  be  both  the  image  and  its  meaning  taken  to- 
gether. This  view  can  be  expressed  by  saying  that 
the  image  present  to  consciousness  means  some- 
thing (some  former  content)  which  is  not  "  present." 
The  introduction  of  the  content  image  does  not 
seem  to  answer  the  question  as  to  how  consciousness 
is  able  to  grasp  what  is  not  "present"  to  it,  and  it 
seems  that  instead  of  trying  to  dodge  the  issue  we 
might  as  well  admit  that  we  can  be  conscious  of 


164  A   SYSTEM   OF   PSYCHOLOGY 

content  which  is  not  presented:    in  which  case  the 
copy-image  is  a  useless  supposition. 

If  we  do  not  postulate  a  specific  image-content, 
the  distinction  between  image  and  idea  is  of  no 
practical  value  unless  we  are  willing  to  make  it  in 
the  way  in  which  it  is  made  in  every-day  language. 
We  do  commonly  discriminate  in  our  use  of  the 
two  terms,  using  "idea"  in  a  general  sense,  and 
"  image"  to  signify  a  form  of  idea  in  which  the  sense 
factors  perceptible  in  a  single  physical  object  or  lim- 
ited group  of  objects,  are  especially  emphasized. 
Thus  when  I  "think"  of  the  pyramids  of  Egypt,  I 
usually  have  a  content  which  combines  vague  ele- 
ments of  geometrical  form  with  more  definite  frag- 
ments of  representations  of  their  probable  builders 
(drawn  of  course  either  directly  or  indirectly  from 
pictures  and  written  descriptions),  with  a  "feeling" 
of  great  distance  from  me,  and  with  some  actually 
presented  muscular  sensations  which  normally  ac- 
company the  lifting  of  a  heavy  weight.  These  are 
not  the  only  factors,  but  they  are  typical  of  what 
the  idea  of  the  pyramids  involves.  It  is  possible 
to  think  of  the  pyramids  in  another  way,  in  which 
the  monuments  themselves,  as  perceptible  objects, 
become  more  prominent,  and  their  relations  to 
other    things    become    less    important.     They   are 


IMAGES   AS   ELEMENTS   OF   CONTENT        165 

then  though!  of  as  concrete  objects  in  which  color, 
form,  and  weight-content  become  predominant,  and 

the  factors  of  distance,  antiquity,  construction- 
problems,  and  personal  and  racial  connections  are 
minimized.  It  is  useful  to  call  the  content  of  the 
former  way  of  thinking  an  idea,  and  the  content  of 
the  latter  an  image,  but  this  is  not  to  be  taken 
as  an  accepted  scientific  usage,  and  the  two  terms 
must  be  used  with  caution. 

So  far  we  have  been  speaking  especially  of  the 
sensation-content  in  imagination;  but  relations  are 
also  imagined.  A  composite  sensory  content  is 
presented  in  a  complex  of  relations,  and  when  we 
imagine  a  similar  content  it  also  is  set  in  and  per- 
meated by  similar  relations.  We  h;ive  shown  above 
that  in  what  we  have  called  an  image  a  limited 
group  of  sensory  content  may  be  important,  as 
against  the  importance  of  a  wider  group  in  what  we 
have  called  an  idea,  and  we  should  also  point  out 
that  in  the  idea  the  relations  which  enter  into  the 
content  are  to  a  large  extent  external  to  the  central 
feature,  while  in  the  image  the  relations  within  the 
central  factors  of  content  are  the  most  important, 
the  external  relations  sinking  into  insignificance.1 

'The  increasing  difficulty  of  arousing  "images,"  which  fre- 
quently accompanies  prolonged  scientific  training,  is  partly 


166  A    SYSTEM   OF   PSYCHOLOGY 

In  the  instances  given  the  central  content  is  con- 
stituted by  the  features  intrinsic  to  the  pyramids 
themselves,  as  perceptible  objects,  and  the  ex- 
ternal relations  are  the  relations  to  geography, 
engineering,  the  peculiarities  of  the  builders,  etc. 

It  is  possible  to  have  an  imaginative  content  in 
which  the  relations  are  the  central  feature,  and  the 
sensory  factors  are  purely  incidental.  Such  a  con- 
tent is  a  further  development  of  what  we  have  above 
described  as  the  idea,  in  the  common  parlance,  and 
is  properly  called  an  abstract  idea,  or  concept.1 

The  three  types  of  content  in  imagination  are 
therefore  what  we  may  call  the  image,  the  idea,  and 
the  concept:  and  we  maintain  that,  as  content,  ab- 
stracted from  the  mode  of  being  conscious  of  them, 
they  involve  only  sensation  and  relation.2 

The  difference  between  the  image  of  a  horse  and 

the  idea  of  a  horse  ought  to  be  already  clear  to  the 

reader.     In  thinking  of  a  horse  of  such  a  size  and 

due  to  the  habits  of  ideating  engendered  by  that  training. 
The  scientist  habitually  apprehends  all  data  in  relation  to 
other  data,  and  loses  to  a  greater  or  less  extent  the  power  to 
isolate  which  is  characteristic  of  the  artist. 

1  The  concept  is  sometimes  identified  with  the  Platonic  Idea, 
and  it  may  seem  that  we  have  committed  ourselves  to  this 
view;  but  that  is  not  quite  the  case. 

2  This  statement  is  to  be  taken  with  the  question  previously 
raised;  whether  feeling  is  ever  strictly  imagined:  but  if  feel- 
ing is  a  form  of  sensation,  the  statement  is  accurate  without 
qualification. 


IMAGES   AS   ELEMENTS   OF   CONTENT        167 

color  and  attitude,  and  with  that  sort  of  qualifica- 
tion only,  you  "have  an  image";  but  if  you  are 
simultaneously  conscious  of  the  usefulness  of  that 
animal  as  a  beast  of  burden,  or  his  importance  as 
an  enemy  in  an  encounter,  or  his  evolutional  re- 
lation to  other  animals,  or  his  need  of  hay  and 
grain,  you  "have  an  idea."  Now  just  carry  this 
differentiation  a  step  further,  and  let  the  particular 
horse  dwindle  in  significance,  and  the  relations 
to  burdens,  oats,  and  so  on,  become  more  emphatic, 
and  you  "have  the  concept"  of  a  horse. 

The  preceding  illustration  makes  apparent  an 
important  fact  about  concepts,  and  one  which  is 
sometimes  overlooked.  There  are  as  many  dif- 
ferent concepts  of  a  horse  as  there  are  different  in- 
dividuals who  conceive  it — in  fact,  each  individual 
has  many  concepts  of  the  equine  species — differing 
according  as  they  emphasize  this  or  that  set  of 
relations;  and  yet  in  the  large  sense  the  concepts 
agree,  since  an  animal  which  will  agree  with  the 
concept  of  the  zoologist  or  the  artist  will  also  satisfy 
the  concept  of  the  hostler.  (The  specimen  which 
is  ranked  high  under  one  concept  may,  however, 
be  ranked  low  under  the  other.) 

While  the  various  concepts  of  a  horse  held  by 
different  individuals  pretty  generally  agree  in  func- 


168  A    SYSTEM   OF   PSYCHOLOGY 

tion,  there  are  other  sorts  of  concepts  which  do  not. 
The  concept  which  one  man  has  of  morality,  or  of 
a  moral  being,  is  often  incommensurable  with  the 
concept  held  by  another  man  on  nominally  the  same 
subject.  This  is  probably  because  the  concepts 
of  neither  are  adequate;  that  is,  neither  has  grasped 
a  really  definite  and  coherent  system  of  relations. 


CHAPTER  XI 

RETENTION,    MEMORY,   AND   RECALL 
i.  Retention 

As  we  have  indicated  already,  one  general  con- 
dition of  imagination  is  the  previous  perception  of 
what  is  imagined,  although  the  content  in  imagina- 
tion does  not  necessarily  have  the  same  form  and 
combination  which  it  had  in  the  former  perception 
or  perceptions.  One  who  has  never  perceived 
light — one  blind  from  birth — cannot  imagine  color,1 
and  a  similar  limitation  applies  to  any  other  sen- 
sation, because  sensation  cannot  be  built  up  from 
anything  else.  As  with  sensations,  so  with  rela- 
tions; if  they  are  not  first  apprehended,  they  can- 
not be  conceived,  although  we  may  form  concepts 
involving  relations  which  have  not  previously  been 
experienced  in  the  exact  combination  in  which  they 
occur  in  the  concept.  A  person  who  had  never 
witnessed  the  transformation  of  a  substance  from 
solid  to  liquid,  and  vice  versa,  might  conceive  of 

1  The  blind  man,  by  noting  what  others  say  about  the  ob- 
jects he  perceives  through  touch,  may  be  able  to  talk  intelli- 
gently about  their  colors,  and  may  not  even  know  that  he 
does  not  know  what  color  is. 

1G9 


170  A    SYSTEM   OF   PSYCHOLOGY 

liquefaction  and  solidification,  but  he  could  do  so 
only  if  he  had  noticed  the  difference  between  the 
two  states  of  substance,  and  had  noticed  modifica- 
tions of  other  sorts. 

The  dependence  of  imagination  on  previous  per- 
ception, although  an  undoubted  fact,  may  not  be 
so  rigid  as  it  is  represented  in  such  statements  as 
those  we  have  made  above.  Just  as  there  are  in- 
stinctive tendencies  to  actions  which  the  individual 
has  not  learned  to  execute — tendencies  due  to  the 
structure  with  which  the  individual  is  endowed  by 
virtue  of  his  place  in  the  animal  kingdom — so  there 
may  be  instinctive  tendencies  to  be  conscious  in 
particular  ways,  due  to  the  nervous  constitution  of 
the  individual  and  not  to  his  experience.  Until 
this  possibility  is  excluded  we  can  merely  say  that 
the  dependence  of  imagination  on  the  previous 
experience  of  the  individual  in  the  way  described 
above  is  the  general  or  usual  fact. 

The  dependence  of  imagination  on  perception  is 
given  the  functional  name  of  retention.  In  some 
way,  the  effects  of  the  past  experience  or  content 
have  been  preserved  and  so  the  present  imagina- 
tion made  possible.  We  do  not  know  exactly 
what  it  is  that  is  retained,  but  psychologists  are 
accustomed  to  designate  it  plurally  as  traces.     The 


RETENTION,    MEMORY,    AND   RECALL        171 

experience  leaves  its  traces,  and  through  some 
activity  initiated  or  facilitated  by  these  traces 
the  content  is  later  revived  as  an  image.  Some 
theorizers  claim  that  these  traces  are  only  phys- 
iological; modifications  in  the  brain  and  its  ap- 
pendages; others  insist  that  there  are  mental  traces 
also. 

On  the  whole,  the  doctrine  of  mental  traces  seems 
to  be  not  an  explanation  of  the  dependence  of  im- 
agination on  perception,  but  a  symbolic  statement 
thereof  which  adds  nothing  to  our  knowledge  on 
the  subject. 

The  first  notable  feature  of  retention  is  the  fact 
that  it  varies  with  the  individual.  One  man,  hav- 
ing experienced  a  certain  content,  retains  it  for  a 
long  time;  another,  under  similar  conditions,  quick- 
ly loses  the  effects  of  what  he  experiences.  This 
difference  shows  plainly  in  memory;  we  find  the 
one  man  able  to  recall  isolated  bits  of  past  experi- 
ence with  ease  and  accuracy,  while  the  other  man 
requires  all  sorts  of  aids  in  order  to  recall  his  simi- 
lar experiences.  The  differences  show  also  in  the 
creative  imagination;  the  wealth  and  facility  of  im- 
agery of  some  individuals  as  against  the  poverty  and 
sluggishness  of  others  is  due  in  part  to  the  extraor- 
dinary way  in  which  all  sorts  of  experiences  stick 


172  A    SYSTEM   OF   PSYCHOLOGY 

iii  the  minds  of  some,  and  the  difficulty  with  which 
they  are  retained  by  others.  A  great  deal  of  individ- 
ual variation  is  due  to  the  factors  we  are  to  take  up 
next;  but  after  allowance  is  made  for  them  there 
seems  to  be  a  residue  of  personal  differences  as  yet 
unanalyzed. 

In  the  second  place,  experiences  which  are 
strongly  impressed,  that  is,  are  strongly  attended  to, 
or  are  repeated  several  times,  are  more  firmly  fixed 
and  retained  than  are  experiences  not  having  that 
advantage.  This  accounts  for  one  sort  of  individual 
peculiarity;  two  persons  may  observe  the  same 
phenomena,  and  afterwards  each  will  be  able  to 
recall  more  fully  the  things  to  which  he  was  specially 
attentive.  A  man  fails  to  recall  the  color  and  style 
of  the  costume  of  the  woman  to  whom  he  talks  for 
half  an  hour,  while  his  wife  after  one  glance  would 
be  enabled  to  recall  these  details  and  a  great  many 
more;  the  man  does  not  attend  to  sartorial  feminine 
details,  although  he  undeniably  sees  them.  The 
effects  of  repetition  are  too  familiar  to  need  ex- 
emplification. 

In  the  third  place,  all  effects  of  experience  tend 
to  disappear  with  the  lapse  of  time.  One  might  say 
(hat  (to  use  an  ancient  analogy)  the  mind  is  like  a 
tablet  of  wax  or  clay,  upon  which  experience  writes. 


RETENTION,    MEMORY,    AND   RECALL        173 

The  firmer  the  wax  and  the  deeper  the  engraving, 
the  more  permanent  the  inscription;  nevertheless, 
all  inscriptions  tend  to  become  in  time  illegible 
through  the  slow  process  of  disintegration  of  the 
surface  of  the  tablet.  Writing  that  is  to  last  as  long 
as  the  tablet  must  be  scratched  in  deep  at  the  first, 
or  else  the  lines  must  be  often  retraced. 

In  many  cases,  content  whose  traces  are  ap- 
parently obliterated  is  really  retained.  As  we  say 
in  common  terminology,  things  forgotten  for  years 
may  return  to  memory  with  great  vividness.  The 
causes  of  this  abeyance  are  obscure;  in  part  it  de- 
pends on  associative  factors,  as  will  be  made  clear 
in  the  next  chapter,  but  over  and  above  the  part 
played  by  association  there  is  an  unexplained  factor 
in  the  variation  in  facility  with  which  the  traces  of 
past  experience,  or  content,  become  active.  This 
slight  obscurity  is  an  important  basis  of  the  pseudo- 
scientific  theories  of  "subconsciousness"  with  which 
we  will  have  to  deal  later.  We  must  remember  that 
retention  is  only  a  name  for  the  fact  that  a  past 
content  is  subject  to  being  re-experienced  in  imagi- 
nation, and  that  the  only  proof  that  a  content  is 
retained  is  in  its  being  imagined;  and,  conversely, 
if  any  content  of  former  experience  is  imagined, 
that  is  prima  facie  proof  that  it  has  been  retained, 


174  A    SYSTEM   OF   PSYCHOLOGY 

even  if  the  period  between  the  original  experience, 
and  the  reproduction  is  fifty  years. 

What  has  been  once  experienced  may  not  return 
to  consciousness  in  imagination,  but  may  be  effec- 
tive in  another  way.  If  you  learn  the  lines  of  a 
poem  to-day,  you  may  have  "forgotten"  them  by 
next  month,  and  be  able  to  repeat  none  of  them. 
Yet,  you  will  find  that  the  relearning  of  the  poem 
requires  less  time  and  energy  than  the  first  learning; 
this  is  largely  a  matter  of  association,  but  not  al- 
together. 

The  retention  of  the  various  impressions  is  facil- 
itated, and  in  fact  the  retention  of  complex  content 
is  made  possible,  by  association.  Under  that  head- 
ing, as  well  as  under  the  headings  of  memory  and 
recall,  retention  must  be  further  discussed. 

2.  Memory 

The  term  memory  is  used  in  psychology  in  prac- 
tically the  same  sense  as  in  common  parlance,  but 
certain  biologists  are  in  the  habit  of  using  the  term 
in  another  way;  a  practice  which  has  brought  about 
a  great  deal  of  confusion  and  unnecessary  conflict 
of  statement.  If  an  animal  acts  upon  any  stimulus 
in  a  way  which  is  the  result  of  previous  stimulations; 
if  his  conduct  or  experience  (assuming  that  we  know 


RETENTION,    MEMORY,    AND   RECALL        175 

something  about  his  experience)  is  based  on  the 
experience  of  the  past,  it  is  said  by  some  writers 
that  the  memory  of  the  past  experiences  or  stimula- 
tions is  demonstrated.  There  would  be  no  objec- 
tion to  this  use  of  the  term  to  designate  the  influ- 
ence of  the  past  nervous  processes  on  those  of  the 
present,  if  it  had  not  been  used  so  long  to  mean 
something  more  specific. 

Specifically,  memory  means  the  consciousness  of 
any  content,  with  the  coincident  consciousness  that 
the  content  has  been  experienced  before  (i.  e.,  rec- 
ognition), and  at  some  more  or  less  definite  date. 
If  I  remember  a  train  wreck  in  which  I  was  a  par- 
ticipant, I  am  conscious  of  it  now,  (in  the  way  of 
reproductive  imagination),  and  also  conscious  that 
it  happened  awhile  ago;  I  may  be  aware  of  the 
exact  period  at  which  it  occurred,  or  I  may  not,  but 
I  at  least  locate  it  in  a  certain  period  of  my  past. 

It  will  perhaps  occur  to  the  reader  that  the 
greater  part  of  my  past  experience,  however  much 
it  may  modify  my  present  experience  and  activity, 
is  not  remembered.  For  example:  my  reading 
and  writing  are  the  result  of  a  number  of  definite 
experiences  of  my  early  life,  yet  I  do  not  remember 
the  content  of  these  experiences,  nor  can  I  remem- 
ber them  if  I  try.     If  some  one  calls  you  by  name, 


176  A   SYSTEM   OF   PSYCHOLOGY 

you  will  reply;  yet  in  ninety-nine  cases  out  of  a 
hundred  you  do  not  remember  your  name  at  the 
time.  You  have  formed  certain  fixed  habits  in 
regard  to  the  particular  sound  to  which  you  answer, 
but  in  few  cases  does  it  occur  to  you  that  you  have 
heard  the  name  in  the  past. 

Many  times  we  reproduce  in  imagination  past 
content,  without  being  aware  that  it  is  past  content; 
the  experience  is  mere  reproductive  imagination, 
not  memory.  The  facility  with  which  non-reminis- 
cent reproduction  occurs  is  at  the  basis  of  a  great 
deal  of  plagiarism  in  literature;  an  author  imagines 
a  situation  or  sentiment  which  is  really  an  exact 
or  approximate  reproduction  of  something  he  has 
previously  read  in  another  author's  writings,  but 
he  does  not  remember  it,  and  so  the  trouble  be- 
gins. A  striking  example  of  this  sort  of  reproduc- 
tion is  found  in  a  short  story  or  miracle-tale  by  a 
well-known  American  author,  who  relates  that  the 
story  came  to  him  in  a  sort  of  dream  at  night.  The 
idea  and  elaboration  of  the  tale  are  so  similar  to  that 
of  one  of  Tolstoi's  short  stories  as  to  raise  the  pre- 
sumption that  the  American  author,  having  read 
Tolstoi's  "Two  Pilgrims,"  at  some  earlier  time, 
reproduced  it  in  an  altered  form,  and  failed  to 
recognize  it. 


RETENTION,    MEMORY,    AND    RECALL        177 

The  important  thing  about  memory  is  the  factor 
of  recognition  by  which  the  reproduced  content  is 
enriched.  We  have  said  enough  to  indicate  that 
this  factor  involves  or  depends  upon  certain  feat- 
ures of  perceived  time;  its  further  treatment  will 
accordingly  be  deferred  to  the  chapter  in  which  time 
is  discussed. 

3.  Recall 

Given  the  fact  that  a  content  once  perceived 
may  be  subsequently  imagined;  to  which  fact  in  the 
abstract  we  give,  as  said  above,  the  name  retention, 
we  inquire  why  the  content  is  imagined — called 
back,  or  recalled,  as  it  were — at  one  time  rather 
than  another;  or  we  may  even  wish  to  know  why  or 
how  it  is  recalled  at  all.  A  part  of  the  mechanism 
of  recall  is  understood,  if  imperfectly. 

In  the  first  place,  the  very  fact  of  retention  im- 
plies a  tendency  to  come  back.  Whatever  content 
has  been  experienced  may  by  virtue  of  that  fact 
alone  return  later  to  consciousness.  The  expres- 
sion "spontaneity  of  the  image"  has  been  applied 
to  this  recurrence-tendency,  the  expression  figuring 
the  image  as  an  entity  with  an  active  force  pressing 
it  toward  the  field  of  consciousness.  We  might 
develop  the  analogy  by  likening  consciousness  to  a 


178  A    SYSTEM   OF   PSYCHOLOGY 

stage,  of  varying  area,  but  strictly  limited,  on  which 
a  vast  crowd  of  players  are  seeking  to  enter.  Some 
of  these  players  are  continually  sent  on  and  off  the 
stage  by  directing  agencies,  but  if  these  agencies 
cease  to  operate,  or  leave  vacancies,  the  images  hav- 
ing the  most  energy  at  the  moment  will  thrust 
themselves  on.  It  is  especially  in  dreams  and  rev- 
eries that  content  seems  to  revive  in  the  way  de- 
scribed by  this  highly  artificial  analogy. 

In  the  second  place,  content  revived  in  memory 
or  imagination  tends  unmistakably  to  disappear 
soon  after  its  entry  into  the  field  of  consciousness. 
It  may  be  kept  before  consciousness  for  varying 
periods  of  time  through  the  effect  of  associative 
factors,  or  in  pathological  cases  the  image  may 
monopolize  consciousness  for  long  intervals;  but 
normally  it  tends  to  fade  soon  after  appearing.  In 
the  terms  of  the  analogy,  the  players  seem  to  be  ex- 
hausted by  the  effort  of  their  appearance  before  the 
foot-lights,  and  need  to  retire  to  some  psychologic 
greenroom  for  long  periods  of  recuperation.  If  it 
were  not  for  this  fortunate  shortness  of  vitality  of 
imaged  content,  the  stream  of  thought  would  soon 
cease  to  flow,  as  in  the  pathological  cases  above 
mentioned. 

The  most  important  factor  in  recall  is  association. 


RETENTION,    MEMORY,    AND   RECALL        179 

The  content  of  past  experience  is  so  linked  together 
that  given  any  perception  or  imagination-content 
before  consciousness  it  tends  to  bring  in  certain 
other  content.  This  linkage  is  designated  as  asso- 
ciation. Because  association  is  of  wider  interest 
than  is  its  function  in  recall,  we  shall  give  it  a  chap- 
ter by  itself. 


CHAPTER  XII 

ASSOCIATION 

i.  The  Principles  of  Association 

Association  is  the  organization  of  experience, 
by  virtue  of  which  the  various  kinds  and  parts  of 
content  constitute  a  whole;  it  is  the  functional  inter- 
connection of  the  objects  of  experience  as  we  find 
them;  not  a  force  or  activity.  The  statement  of 
the  principles  or  laws  of  association  is  by  no  means 
an  explanation  of  anything,  but  simply  a  convenient 
summary  of  observed  facts. 

I.  The  Principle  of  Integration. 

The  total  content  of  consciousness  under  nor- 
mal conditions  is  unified  or  organized  into  a  unity. 
The  various  factors  which  we  distinguish  are  given 
not  as  distinct  elements  fortuitously  collocated,  but 
as  inseparable  parts  of  the  total  content.  This 
organization  or  integration  has  two  directions:  (1) 
Organization  in  simultaneity,  and  (2)  Organiza- 
tion in  succession. 

(1)  We  find  organization  at  any  given  instant  in 

the  content  of  consciousness.     If  we  liken  the  total 

180 


ASSOCIATION  181 

content  to  a  rope,  a  cross-section  of  the  rope  repre- 
sents the  state  of  the  content  at  any  given  time.  If 
we  analyze  this  cross-section  of  content  we  find  it 
reducible  to  the  factors  already  enumerated  (sen- 
sation and  relation,  with  feeling  and  possibly  image; 
the  association  as  content,  is  relational).  We  do 
not  suppose  that  these  elements  originate  individ- 
ually and  then  unite,  like  chemicals  thrown  into  a 
beaker;  we  consider  them  as  arising  in  the  com- 
binations in  which  they  are  found,  and  likewise 
declining;  by  both  processes  modifying  the  com- 
plexes in  which  they  exist. 

We  find  the  cross-section  of  content  made  up  of 
several  smaller  unities — again  like  the  rope,  al- 
though the  rope  strands  are  merely  contiguous, 
while  these  complexes  are  more  or  less  intercon- 
nected, the  same  element  often  forming  an  element 
of  several.  If  you  are  looking  at  a  rotating  color- 
wheel,  and  also  thinking  of  the  end  of  the  hour,  the 
content  of  your  consciousness  is  composed  of  several 
subdivisions  somewhat  like  the  following:  A.  A 
complex  of  color  and  sound  sensations  with  rela- 
tions and  images  (which  you  call  the  color-wheel) 
with  certain  emotional  factors,  perhaps  interest, 
perhaps  ennui.  These  tend  to  form  a  special 
group,  possessing  an  internal  coherence  not  shared 


182  A    SYSTEM   OF   PSYCHOLOGY 

with  the  other  groups  described  below,  although  the 
emotional  element,  and  perhaps  some  sensational 
elements,  may  be  common.  B.  Your  thinking  of 
the  end  of  the  hour  depends  on  the  function  of  a 
specific  group  of  content  (mostly  imaginative),  both 
sensory  and  intellectual,  with  emotional  coloring, 
perhaps  of  desire,  impatience,  or  aversion,  or  per- 
haps the  ennui  above  mentioned.  Imagery  of  the 
length  of  time  yet  to  elapse,  of  the  occupations  to 
commence,  of  the  heat  of  the  sun  outside,  and  so  on, 
may  supply  the  nucleus  of  this  division  of  content. 
C.  A  third  group,  or  set  of  groups,  is  composed  of 
bodily  feelings,  with  certain  sights  and  sounds  not 
involved  in  the  first  mentioned  groups — the  mov- 
ing of  shadows  across  the  wall;  the  buzzing  of  a 
fly;  the  pressure  of  the  clothing  on  the  skin;  the 
warmth  or  chilliness  of  parts  of  the  body;  visceral 
sensations,  thirst,  and  so  on;  with,  perhaps,  certain 
emotional  coloring  not  germane  to  the  other  groups. 
Each  of  the  three  groups  mentioned  is  separable 
under  scrutiny  into  several  subgroups.  The  anal- 
ysis, or  a  stage  in  the  analysis,  of  group  C  is  obvi- 
ous. In  group  A  the  treatment  is  not  so  easy. 
Perhaps  we  find  the  visual  factors  forming  the  nu- 
cleus of  one  subgroup,  and  the  auditory  that  of  an- 
other, but  in  some  cases  it  seems  that  the  auditory 


association  is:; 

and  visual  factors  are  united  with  each  other  as 
firmly  as  auditory  with  auditory  or  visual  with 
visual. 

In  many  cases  we  find,  before  reaching  the  ulti- 
mate elements,  peculiar  small  groups  which  are 
called  fusions,  in  which  several  sensations  of  the 
same  mode  can  be  discriminated.  Thus,  the  hue 
of  the  revolving  wheel  may  be  a  fusion  of  several 
primary  colors;  purple  is  a  fusion  of  red  and  blue; 
the  taste  of  the  lemon-drop  in  your  mouth  is  a  fusion 
of  sweet,  sour,  and  a  slight  bitter.  It  is  a  question 
whether  we  ought  not  to  include  under  the  term 
"fusion"  combinations  not  of  the  same  mode,  as 
warmth  and  touch  sensations,  taste,  and  smell. 

In  applying  the  name  "fusion,"  we  mean  to  im- 
ply that  while  these  combinations  function  as  units 
in  practically  the  same  way  as  do  elementary  sen- 
sations, they  can  be  perceived  as  complex,  by  atten- 
tive observation.  In  this  analysis  the  complex  con- 
tent changes:  it  is  a  commonplace  that  the  taste  of 
lemonade  is  not  simply  the  taste  of  lemon  plus  the 
taste  of  sugar,  but  has  an  individuality  of  its  own. 
This  change  is  readily  made  intelligible  if  we  re- 
member that  in  analyzing  a  fusion  we  bring  in  or 
emphasize  relations  which  were  not  previously  in 
the  content,  or  else  were  not  vivid;   and  that  in  ex- 


1S4  A   SYSTEM   OF   PSYCHOLOGY 

periencing  separately  the  elements  of  the  fusion,  as 
the  sour  and  the  sweet,  we  have  in  the  contents  a 
different  relational  nexus,  and  perhaps,  also,  differ- 
ent imaginative  sensory  factors  from  those  present 
when  the  fusion  is  experienced  even  with  attempt 
at  analysis.1 

(2)  We  have  said  that  content  is  organized  not 
only  in  simultaneity,  but  also  in  succession;  it  is 
integrated  in  longitudinal  as  well  as  in  cross-section. 
The  present  content  is  essentially  connected  with 
that  of  the  future  and  of  the  past.  Moreover,  each 
group,  subgroup,  and  element  has  an  actual  life 
history.  No  sensation,  for  example,  comes  into 
existence  instantaneously;  it  rises,  reaches  a  maxi- 
mum of  intensity,  and  then  falls  back.  So  a  cross- 
section  of  any  portion  of  the  content  of  consciousness 
at  any  time  represents  only  a  stage  in  its  develop- 
ment. In  this  the  analogy  to  .the  rope  comes  up 
again ;  the  rope  is  made  up  of  fibres,  each  having  a 
definite  length,  short  as  compared  with  the  length 
of.  the  rope;   but  here  also  the  analogy  fails,  as  there 

1  The  student  may  be  surprised  at  the  way  in  which  the 
"individuality"  of  the  lemonade  taste  may  be  made  to  de- 
crease. Take  a  glass  of  lemon-juice  solution  and  a  glass  of 
sugar  solution,  of  such  strength  that  when  equal  quantities 
of  each  are  mixed  in  a  third  glass  a  good  lemonade  results. 
Then  taste  the  three  solutions  in  alternation,  making  careful 
comparisons. 


ASSOCIATION  185 

is  nothing  in  the  rope  to  represent  the  temporal 
development  of  the  subgroups. 

It  is  clear  that  psychological  research  has  a  two- 
fold problem  at  any  point  which  it  attempts  to  in- 
vestigate from  the  side  of  content:  first,  to  analyze  a 
given  content,  and,  second,  to  trace  the  development 
thereof.  The  solution  of  the  second  problem  is 
much  more  difficult  than  that  of  the  first,  for  it 
really  involves  the  solution  of  the  first  for  a  number 
of  successive  stages.  If  I  wish  to  study  emotion 
of  a  certain  type,  for  example,  I  must  not  only 
analyze  such  emotion  at  a  given  moment  or  stage, 
but  must  also  make  or  assume  analyses  at  several 
moments  in  its  life  history,  in  order  to  understand  its 
development  and  the  longitudinal  connection  of  its 
elements.  The  same  treatment  should  eventually 
be  applied  to  the  total  stream  of  consciousness;  by 
performing  adequate  analyses  at  enough  points  in 
the  life  history  of  the  individual  we  might  get  a 
comprehensive  view  of  the  psychic  life. 

II.  The  Principle  of  the  Middle  Term,  or  Medi- 
ate Association. 

Two  contents  or  factors  in  content  which  are  not 
strongly  linked  directly  may  be  linked  each  to  a 
third  term,  or  they  may  be  linked  through  several 
intermediaries;   and  this  mediate  linking  of  the  two 


186  A    SYSTEM   OF   PSYCHOLOGY 

may  be  more  important  practically  than  the  direct 
associations  with  the  intervening  term  or  terms. 
If  M  and  N  are  two  factors  in  content  which  are  so 
far  apart  in  time  that  M  has  practically  faded  out 
before  N  commences  to  rise,  but  if  P  occurs  while 
M  is  vivid,  and  is  still  effectively  on  the  stage  when 
N  becomes  vivid,  the  three  may  form  a  fibre  in  suc- 
cessive association,  uniting  M  with  N  through  P. 
The  name  "Bud"  and  the  jaw  movement  of  gum- 
chewing  are,  perhaps,  associated  in  your  experience 
not  because  you  have  heard  the  one  and  seen  the 
other  at  the  same  time,  but  because  each  has  been 
associated  in  simultaneity  with  some  other  feature 
or  features  of  an  individual.  Other  examples  will 
readily  occur  to  the  reader.  Emotional  content  is 
especially  apt  to  form  a  third  term  in  this  way. 
Those  contents  which  have  been  experienced  to- 
gether under  the  influence  of  strong  emotion  are 
more  firmly  associated  thereby,  other  things  being 
equal,  and  what  has  been  experienced  with  a  certain 
quality  of  emotion  at  one  time  is  associated  medi- 
ately with  what  has  been  experienced  at  another 
time  under  the  same  sort  of  emotional  conditions. 

III.     The  Principle  of  Intellectual  Association. 

The  association  of  two  elements  or  groups  of 
content  is  stronger  in  so  far  as  a  definite  relation 


ASSOCIATION  187 

or  system  of  relations  is  perceived  as  subsisting  be- 
tween them.  If  I  notice  that  two  things  are  simi- 
lar or  dissimilar  in  some  regard,  or  if  I  notice  that 
one  immediately  follows  the  other,  or  if  I  perceive 
or  imagine  that  one  is  the  cause  of  the  other,  or 
that  they  are  spatially  related  in  a  certain  way, 
these  things  are  more  strongly  associated  than  if 
the  relations  had  not  been  noticed. 

IV.  The  Principle  of  Redintegration.  (Principle 
of  Reinstatement;  Principle  of  Associative  Recall.) 

When  any  content  appears  in  imagination  or 
apprehension  there  is  ipso  facto  a  probability  that 
the  other  contents  associated  with  it  will  appear 
also:  in  other  words,  a  total  content  tends  to  be 
reinstated  as  soon  as  a  part  of  it  is  introduced. 
The  events  are  analogous  to  what  happens  when 
you  try  to  pull  a  weed  out  of  a  tangle  in  the  water; 
you  find  that  you  pull  out  a  large  quantity  of  others 
which  are  ensnarled  with  it. 

There  are  several  ways  in  which  this  revival  of 
past  content  through  association  may  take  place. 

(1)  The  associated  factor  may  reappear  in  the 
same  organization  as  before.  If  you  meet  to-day  a 
person  whom  you  met  yesterday,  you  may  be  again 
conscious  of  some  of  the  circumstances  in  which 
you  met  him  before.     The  stage  setting,  as  it  were, 


188  A    SYSTEM   OF   PSYCHOLOGY 

in  which  he  was  placed  is  revived  as  soon  as  he 
reappears.  In  repeating  the  words  of  a  poem  the 
imagery  and  emotions  appropriate  to  the  words  and 
phrases  which  have  been  associated  with  them  come 
up  in  proper  synthesis.  Moreover,  the  successively 
associated  factors  are  repeated  in  their  former 
sequences;  the  words  of  the  poem  are  recalled  nat- 
urally in  the  order  in  which  they  have  been  linked 
in  the  text  of  the  past  experience.  The  series  of 
words  forming  the  poem  are,  as  the  result  of  the 
past  experience,  associated  in  a  whole  in  which 
imagery  and  emotional  coloring  bind  them  together 
in  multiple  bonds.  Words  and  phrases  in  one 
portion  of  the  poem  are  so  linked  by  intermediate 
terms  and  directly  with  phrases  in  other  portions, 
that  having  once  commenced  the  recitation  of  the 
poem  we  are  in  little  danger  of  being  carried  off 
the  thread  into  something  else.  But  if  we  were 
restricted  to  associations  between  simultaneous  or 
immediately  successive  factors,  we  would  be  apt, 
when  we  have  recalled  the  line  "lead  kindly  light," 
to  finish  it  up  "of  other  days  around  me,"  and  still 
more  apt  to  finish  "  Yes,  that  was  the  reason  (as  all 
men  know),  in  this  kingdom  by  the  sea,  that  the 
wind  rame,"  by  adding  "up  out  of  the  sea,  and  said, 
'()  mists,  make  room  for  me.'" 


ASSOCIATION  1S9 

In  poetry  the  enveloping  rhythm  furnishes  a  con- 
tinuous bond  in  association  which  would  operate  to 
prevent  transitions  such  as  those  we  have  just  sug- 
gested; in  some  cases,  however,  the  transitions  from 
one  text  to  another  would  not  alter  the  rhythm, 
especially  if  it  is  a  matter  of  different  bits  from  the 
same  poem.  In  prose,  of  course,  there  is  nothing 
but  normal  mediate  associations  to  prevent  the  va- 
rious texts  we  have  memorized  from  being  "pied" 
in  recall. 

The  rhyme  furnishes  in  some  poetry  an  addi- 
tional means  of  association.  Certain  sounds  are 
given  by  their  position  in  the  rhythmic  structure, 
and,  by  repetition,  an  especial  emphasis  and  dura- 
tion in  consciousness,  so  that  there  is  immediate 
association  between  one  rhyme  word  and  the  ones 
preceding  and  following  it.  Rhymes,  alliterations, 
and  all  such  devices  are  to  be  considered  as  means 
for  the  production  of  associative  bonds,  tying  the 
stanzas  together  in  a  more  unified  whole  than 
would  otherwise  be  achieved.  They  are  not  aes- 
thetic ends,  but  are  mechanism  for  the  production 
of  ends  aesthetic,  or  even  practical,  as  in  the  jingles 
by  which  we  manage  to  fix  elusive  facts  of  history. 

(2)  The  time  order  of  the  former  content  may 
be  modified  in  the  recall.     The  setting  in  which  I 


190  A    SYSTEM    OF    PSYCHOLOGY 

saw  the  person  yesterday  may  not  recur  when  I  see 
or  think  of  him  to-day,  but  may  come  in  afterward. 
On  the  other  hand,  things  which  were  experienced 
in  succession  may  be  imagined  or  remembered  simul- 
taneously, or  when  one  is  perceived  the  others  are 
recalled  simultaneously  with  it.  After  the  child  has 
experienced  the  sight  of  the  medicine,  followed  by 
the  taste,  and  perhaps  subsequent  nausea,  the  mere 
sight  of  the  proffered  mixture  arouses  coincidently 
the  other  factors. 

(3)  Very  frequently  contents  which  have  been 
mediately  associated  become  immediately  associ- 
ated through  the  dropping  out  of  the  middle  terms 
or  term.  Seeing  a  load  of  coal  put  in  suggests  the 
sifting  of  ashes;  hearing  a  huckster  announcing 
soft  crabs  suggests  rinding  a  gold  watch;  yet  the 
various  terms  which  in  the  beginning  mediated  the 
association  do  not  occur  to  me  until  afterward,  if 
at  all.  This  sort  of  modification  of  association  by 
the  elimination  of  terms  is  so  common  that  it 
largely  escapes  our  notice. 

V.  The  Principle  of  Relative  Strength. 

We  may  say  that  the  possibility  of  the  reinstate- 
ment of  any  content  through  association  with  an- 
other content  present  to  consciousness  is  propor- 
tional to  the  strength  of  the  association,  and  that 


ASSOCIATION  191 

therefore  if  a  given  factor,  M,  is  associated  with  two 
contents,  P  and  Q,  which  are  too  different  to  come  in 
together,  the  one  most  strongly  associated  with  M 
will  come.  (The  so-called  principle  of  conflicting 
associations.)  But  if  P  is  associated  with  M,  and 
also  with  K,  which  is  just  disappearing,  and  with  S, 
which  is  present  throughout,  whereas  Q  is  asso- 
ciated only  with  M,  P  may  be  brought  in,  in  spite  of 
the  stronger  connection  of  M  with  Q  than  with  P;  for 
the  other  associations  assist  in  reviving  P.  (This 
is  sometimes  called  the  co-operation  of  associa- 
tions.) We  may  illustrate  by  the  poetical  frag- 
ments given  above:  the  Longfellow  poem  may  be 
much  more  familiar  to  you  than  the  one  by  Poe, 
and  hence  "  the  wind  came  up"  more  strongly  asso- 
ciated with  "from  out  of  the  sea"  than  with  "out 
of  a  cloud  by  night."  In  that  case,  if  some  one 
should  repeat  to  you  "the  wind  came  up,"  alone, 
you  would  finish  the  line  Longfellow-wise.  When 
the  earlier  lines  of  the  poem  of  Poe  are  given  you 
too,  you  finish  the  line  accordingly  because  of  the 
co-operating  associations  of  "out  of  a  cloud  by 
night"  with  these  earlier  lines. 

The  concept  of  "strength"  of  association  must 
be  admitted  to  be  very  vague.  After  all,  it  is 
constructed,  like  the  concept  of  retention,  from  the 


192  A    SYSTEM   OF   PSYCHOLOGY 

fact  that  things  do  come  back,  and  that  they  come 
back  in  specific  ways,  as  we  have  been  trying  to 
show.  When  we  say  that  M  is  more  strongly  asso- 
ciated with  P  than  with  Q,  we  mean  simply  that 
unless  some  other  factor  operates,  M  will  call  up  P 
rather  than  Q. 

The  strength  of  any  association  depends,  like  the 
retention  of  content,  upon  the  vividness  with  which 
the  associated  factors  are  impressed,  and  on  the 
repetition  of  the  impressions  in  succession  or 
simultaneously.  This  needs  no  extended  discus- 
sion here.  The  strength  of  the  association  is  also 
increased  by  each  recall  through  the  association; 
the  oftener  M  calls  up  P,  the  more  readily  it  will 
do  so. 

2.  Voluntary  Recall 

We  often  make  the  attempt — successful  or  not — 
to  recall  some  definite  content.  This  attempt,  or 
performance,  seems  at  first  inspection  to  be  absurd. 
If  I  am  not  conscious  of  a  given  content  how  do  I 
know  what  it  is?  The  recall  is  actually  set  in 
motion,  or  we  attempt  to  set  it  in  motion,  by  a  proc- 
ess which  is  naively  described  as  "Thinking  of  the 
things  we  know  to  be  associated  with  the  required 
content,"  trusting  to  the  associations  to  bring  the 


ASSOCIATION  193 

required  content  before  consciousness.  But  we 
ask:  How  do  I  know  what  is  associated  with  the  re- 
quired content,  if  I  do  not  know  what  that  content 
is?  And  how  do  I  manage  to  bring  up  the  things 
associated  with  the  required  content? 

The  fact  is  that  these  contents  are  already  there, 
or  some  of  them  are,  and  it  is  their  presence  that 
brings  the  desire  for  the  sought  factor.  Some  fac- 
tor, M,  comes  up,  which  is  in  a  certain  relation  to 
something  else,  and  yet  the  present  factor  and  the 
relation  do  not  bring  up  the  missing  one.  So  I 
attend  to  some  other  factor  suggested  by  M,  to  see 
what  it  will  suggest;  if  this  does  not  suggest  some- 
thing satisfying  the  relation,  it  may  suggest  some- 
thing which  will  make  the  proper  suggestion.  For 
example:  I  see  across  the  room  a  man  whose  name 
I  do  not  remember.  The  fact  that  I  am  approach- 
ing him  calls  up  the  impending  salutation,  and  the 
relation  of  the  visible  man  to  a  name;  yet  the  name 
is  not  recalled.  The  appearance  of  the  man  recalls 
Mr.  Blank,  at  whose  house  I  was  introduced  to  the 
man;  I  hold  the  idea  of  Mr.  Blank  and  the  meet- 
ing in  consciousness,  and  these  factors  recall  the 
joke  Mrs.  Blank  made  on  the  man's  belying  his 
name;  still  the  name  does  not  appear,  although  I 
am  getting  "  warm."     This  incongruity  of  man  and 


194  A   SYSTEM  OF  PSYCHOLOGY 

name,  if  attended  to,  may  suggest  his  voice,  and 
then  the  name — Singer — may  come  up  at  once. 
This  is  a  typical  instance  of  voluntary  recall,  and 
the  only  voluntary  element  is  the  "holding  of  the 
attention  on  certain  content,"  to  get  the  maximal 
effect  from  its  associations. 

Sometimes  the  factors  on  which  the  attention  is 
held  in  voluntary  recall  are  relations.  Thus,  in 
trying  to  think  of  a  man's  name  the  relation  of 
rhyming  with  something  may  come  up,  and  by  at- 
tending to  that  relation  a  rhymed  word  will  in 
many  cases  appear,  and  assist  in  the  final  solution 
of  the  problem.  Sometimes  we  start  with  a  num- 
ber of  relations  and  seek  that  which  will  fulfil 
them;  start  with  a  concept,  in  short,  and  let  it  de- 
velop into  an  idea.  This  is  conspicuously  the  case 
in  the  solution  of  riddles. 

3.  The  Probable  Physiological  Basis  of  Association 

The  exact  physiological  bases  of  association  are 
as  yet  unknown.  We  assume  that  there  are  some 
processes  in  the  brain  corresponding  to  these  func- 
tions, but  what  they  are  or  where  they  are  located 
has  not  yet  been  discovered.  It  has  been  quite  the 
fashion  to  ascribe  association  to  the  formation  of 
"brain-paths,"  lines  of  conduction  from  one  cell  or 


ASSOCIATION"  195 

group  of  cells  to  another;  but  this  was  intended 
only  as  a  picturesque  metaphor;  for,  taken  liter- 
ally, it  would  imply  a  special  cell  or  group  of  cells 
for  each  idea  capable  of  being  associated  with  an- 
other, or  other  absurdities  which  no  psychologists 
or  physiologists  entertain.  Some  theorizers  have 
assumed  the  existence  of  a  special  association  cen- 
tre in  the  frontal  lobes,  but  so  far  there  is  not  much 
real  evidence  for  the  theory. 


CHAPTER   XIII 

PERCEPTION 
i.  The  General  Nature  of  the  Content  in  Perception 

We  have  already  indicated  that  perception  com- 
prises more  than  intuition  or  direct  apprehension; 
that  is  to  say,  that  the  content  in  perception  in- 
cludes more  than  sensations  and  relations.  Per- 
ception1 is  the  consciousness  of  a  content  which  in 
usual  cases  includes  (1)  present  sensations,  (2) 
present  relations  interwoven  with  the  sensations 
and  other  content,  (3)  imaginative  content,  and 
(4)  emotional  factors.  With  regard  to  the  third 
category,  we  ought  to  say  at  once  that  by  far  the 
most  important  thing  in  the  imagined  portion  of 
the  content  of  perception  of  adults  is  conceptual. 
The  merely  sensuous  imagery  may  play  a  part,  but 
it  is  relatively  unimportant  in  comparison  with  the 
systematized  relationships  in  which  the  intuited 
content  is  placed. 

Suppose  I  stand  some  distance  from  a  railroad 

track  and  observe  a  passing  train:   I  obtain  a  com- 

1  "Perception"  is  used  loosely  in  common  discourse  for  any 
sort  of  understanding  or  comprehension.  We  are  using  it  here 
in  a  strict,  technical  sense. 

196 


PERCEPTION  L97 

plex  perception-content  which  it  is  worth  our  while 
to  analyze.  In  the  first  place,  there  are  the  ele- 
ments of  light  and  color.  The  locomotive,  the  cars, 
the  smoke,  the  trees  which  form  the  background, 
are  presented  as  an  aggregate  of  many  hues  and 
shades.  At  the  same  time  are  presented  sensations 
of  other  modes;  the  panting  of  the  locomotive  and 
roaring  of  the  wheels  and  shriek  of  the  whistle,  the 
smell  of  the  smoke,  and  the  trembling  of  the  ground. 
These  sensations  are  only  a  small  part  of  the  total 
content.  Not  only  do  I  notice  the  spatial  relation 
of  the  colors — that  the  dark  and  shiny  locomotive 
precedes  the  red  cars,  that  the  smoke  hangs  above 
the  trees  and  spreads  out — but  I  notice  the  likeness 
of  the  smoke  to  the  clouds,  the  contrast  betwTeen  the 
red  and  the  green  of  the  trees,  and  so  on.  More- 
over, I  am  conscious  that  it  is  a  passenger  train, 
which  means,  probably,  that  I  imagine  people 
within  it:  I  imagine  the  wheels  turning,  although  I 
cannot  see  their  rotation;  I  image  other  features 
according  to  my  habits  of  thought.  Certainly, 
whatever  I  perceive  of  a  sensory  nature,  beyond  a 
few  patches  of  color  and  a  few  sounds  and  smells 
and  the  vibration,  is  imagined. 

More  important  than  the  intuited  content,  or  the 
imaged  sensory  content,  is  the  fact  that  I  recognize 


198  A    SYSTEM   OF   PSYCHOLOGY 

the  object  as  a  railroad  train;  I  am  aware  of  its 
relations  to  iron  tracks,  stations,  transfer  of  pas- 
sengers, purchasing  of  tickets,  and  numberless  other 
details,  some  of  which,  like  the  passengers  inside, 
may  be  imaged,  but  the  greater  number  of  which 
are  not.  On  account  of  this  conceptual  synthesis 
of  the  content,  my  train  as  I  perceive  it  is  vastly 
different  from  the  train  a  savage  would  perceive 
from  my  view-point,  although  he  would  experience 
the  same  sorts  of  sensations  and  the  same  pre- 
sented relations  as  I  do.  So,  too,  the  train  as  the 
content  of  the  railroad  man  or  of  the  farmer  would 
differ  largely  from  mine,  because  in  each  case  a 
different  set  of  relations  would  be  emphasized  by 
the  individual's  past  experience,  and  be  aroused  to 
unite  as  a  concept  with  the  intuited  factors. 

The  function  of  the  concept  in  perception  is 
sometimes  called  apperception.  The  concept  and 
the  imaged  sensory  factors  connected  with  it  are 
called  the  apperception  mass,  and  the  directly  ap- 
prehended sensations  and  relations  the  apperceived 
factors.     These  terms  are  now  falling  into  disuse. 

The  concept  is  built,  developed,  and  extended, 
by  experience.  Any  new  perception  is  apt  to  mod- 
ify the  concept  which  functions  therein.  The 
first  time  an  individual  rides  on  a  train,  which  be- 


PERCEPTION  199 

fore  he  has  merely  seen — and  heard— from  a  dis- 
tance, he  apprehends  a  lot  of  new  relations  which 
thereafter  recur  in  the  concept.  If  perchance  he 
sees  some  one  run  over,  the  train  is  perceived  with 
new  elements  of  relation,  and  henceforth  all  trains 
will  be  perceived  in  the  light  of  a  concept  modified 
by  those  relations. 

Changes  in  the  concept  may  take  place  also 
without  perception;  when  the  sensory  content 
which  fills  out  the  concept  and  makes  it  concrete 
is  only  imaged.  When,  for  example,  I  speak  to 
you  of  trains,  you  imagine  them;  your  concept  at- 
taching itself  to  the  sensory  content  which  you  call 
up,  just  as  if  it  were  apprehended  in  reality.  If 
then  I  tell  you  of  the  running  over  of  some  one,  or 
explain  the  problems  of  maintaining  equilibrium  on 
curves,  or  providing  sufficient  elasticity  to  allow 
starting  and  stopping,  the  imaged  content  takes  in 
new  details,  and  the  modified  concept  will  govern 
your  next  perception  of  a  train. 

We  may  reach  a  stage  of  conceptual  development 
in  which  concepts  are  modified  without  the  neces- 
sity of  filling  in,  even  imaginatively,  with  sensory 
content.  New  relational  factors  are  learned,  usu- 
ally by  inference,  and  these  are  amalgamated  with 
the  concept  already  in  existence:    or  the  process 


200  A    SYSTEM   OF   PSYCHOLOGY 

may  be  one  of  elimination,  certain  supposed  prop- 
erties of  a  certain  thing  being  found  not  properly 
belonging  to  it,  and  the  concept  being  contracted 
accordingly.  It  is  difficult  to  show  instances  of 
this  purely  intellectual  modification  of  concepts  in 
every-day  life  (although  it  undoubtedly  occurs 
there),  but  in  science  the  process  is  clearly  exhib- 
ited. The  atom,  for  instance,  was  conceived  with 
an  approach  to  adequacy,  and  as  new  facts 
were  learned  the  concept  was  modified  accordingly, 
until  it  has  become  vastly  different  from  that  held 
by  scientists  twenty-five  years  ago.  Yet  sensory 
imagination  plays  little  part  in  this  readjustment, 
being  more  a  disturbing  factor  than  otherwise.  In 
less  abstruse  cases,  where  imagination  might  have 
a  role,  the  scientist  economizes  energy  and  in- 
creases accuracy  by  leaving  it  out.1 

The  development  of  perception  is,  therefore,  in 
reality,  the  development  principally  of  conception. 
The  sensory  factors  are  very  simply  controlled,  and 


1  We  may  distinguish  three  types  of  conceptual  modifica- 
tion, which  possibly  correspond  to  stages  of  mental  develop- 
ment. These  stages  are:  (1)  The  perceptual,  (2)  the  concrete 
imaginative,  and  (3)  the  conceptual  modification  of  con- 
cepts. Possibly  animals  are  restricted  to  the  first  type,  but 
of  this  we  have  no  proof.  In  the  case  of  adult  human  beings 
(he  first  <\|>e  rarely  occurs  pure,  but  undoubtedly  many  per- 
sons never  attain  in  the  slightest  to  the  third  type. 


PERCEPTION  201 

only  a  small  amount  of  experience  is  needed  to 
make  them  practically  as  perfeet  as  they  ever  may 
be.  The  individual  is  endowed  by  his  parentage 
with  his  sensory  apparatus;  it  is  developed  in  part 
through  the  demands  made  upon  it  by  his  experi- 
ence, but  largely  through  the  general  development 
of  the  body,  just  as  the  hair  grows.  A  little  prac- 
tice is  needed  to  direct,  focus,  and  converge  the 
eyes  properly,  but  these  adjustments  develop  in 
the  individual  largely  of  themselves,  demanding 
only  use  to  fix  the  development.  The  child  of  a 
few  years  is  equipped  sensationally  as  well  as  he 
ever  will  be,  and  much  better  than  he  will  be  in 
adult  life. 

2.  Perception,  Illusion,  and  Hallucination 

Perception  may  be  "right"  or  "wrong."  The 
incoming  sensory  content  may  be  united  with  the 
proper  concept,  or  it  may  be  united  with  an  egre- 
giously  inappropriate  concept.  The  former  case, 
where  the  perception  is  "  right,"  we  are  accustomed 
to  call  true  or  normal  perception,  and  the  latter  case 
we  call  illusion.  To  take  an  extreme  case:  a 
sheet  is  hanging  on  a  bush  in  the  dark,  and  some 
one  seeing  it  unites  the  visual  appearance  with  his 
concept  of  a  ghost:    his  perception  is  illusory,  yet 


202  A    SYSTEM   OF   PSYCHOLOGY 

he  may  receive  sensory  and  relational  intuition- 
content  practically  agreeing  with  that  of  another 
person  who  unites  it  with  the  appropriate  concept 
and  perceives  truly. 

The  freshman  who  looked  at  the  page-heading 
in  my  copy  of  the  Critique  of  Pure  Reason  and 
exclaimed  in  amazement,  "Transcontinental  dia- 
lect! What  in  the  dickens  is  that?,"  probably  re- 
ceived from  the  printed  words  sensations  not  very 
different  from  those  I  received;  but  since  one,  in 
reading,  notices  but  a  part  of  the  letters  in  a  word, 
imagining  or  dispensing  with  the  rest,  the  fresh- 
man's unfamiliarity  with  the  transcendental  dia- 
lectic resulted  in  the  noticed  letters  calling  up  the 
concepts  associated  with  them  in  his  experience.  If 
you  see  a  man  on  the  street,  and  say,  "  Ah,  there  is 
Richard  Roe;  I  must  speak  to  him  about  that 
book,"  and  then  find  on  overtaking  him  that  it  is 
not  Roe  at  all,  but  John  Doe,  who  scarcely  re- 
sembles Roe  on  close  scrutiny,  your  mistake  lies  in 
that  to  certain  sensory  factors  intuited  you  added 
the  imagined  facial  expression,  etc.,  of  Richard 
Roe,  and  the  concept  you  have  formed  of  that 
gentleman. 

The  contrast  between  perception  and  illusion 
disappears  when  we  examine  them  closely.     The 


PERCEPTION  203 

extreme  cases  we  have  instanced,  where  the  con- 
cept is  hopelessly  inadequate,  are  few  in  compari- 
son with  the  cases  in  which  the  inadequacy  is  not 
so  pronounced.  Many  persons  at  the  present 
time  conceive  a  trolley-car  as  dragged  along  by  the 
trolley,  vaguely  supposing  that  the  "current"  in 
the  wire  carries  the  trolley  along  with  it,  as  the 
cable  "grip"  is  carried  by  the  cable.  When  such 
a  person  has  found  out  the  way  in  which  a  street- 
car is  actually  propelled,  the  content  of  his  percep- 
tion of  a  car  is  appreciably  changed;  and  yet  the 
error  is  of  no  practical  consequence  to  the  mistaken 
man  as  long  as  he  does  not  attempt  to  fill  a  posi- 
tion as  a  carman.  On  the  other  hand,  a  slightly 
inadequate  perception  of  a  car  as  regards  its  speed, 
or  of  an  invalid  as  regards  his  condition,  may  have 
the  most  serious  consequences.  Perhaps  the  truest 
statement  would  be  that  none  of  our  conceptions  and 
perceptions  are  quite  adequate,  but  some  are  near 
enough  to  adequacy  for  practical  purposes. 

One  special  type  of  "false"  perception  has  re- 
ceived the  name  of  hallucination.  In  this  the  in- 
tuited sensational  factor  is  reduced  to  a  minimum, 
or  at  least  is  not  of  any  practical  consequence  in 
the  total  perception.  The  essential  sensory  fac- 
tors are  all  supplied  by  imagination,  but  the  com- 


204  A    SYSTEM   OF   PSYCHOLOGY 

plex  is  mistaken  for,  or  at  least  has  the  apparent 
character  of,  reality.  Hallucinations  occur  to  al- 
most all  of  us  in  what  we  call  dreams,  and  some- 
times in  waking  life,  but  waking  hallucinations  are 
usually  attendants  of  mental  disease. 

Hallucination  and  illusion  are  to  be  distinguished 
from  pseudo-hallucination  and  pseudo-illusion. 
Pseudo-hallucination  is  often  found  in  dreams, 
where  the  content  has  the  semblance  of  perception- 
content,  except  that  the  dreamer  is  distinctly  con- 
scious that  it  is  a  dream,  and  not  real.  So,  in  wak- 
ing life,  there  often  occur  experiences  which  have 
many  of  the  marks  of  perceptions,  but  which  we 
know  are  imaginations.  There  is  something  about 
the  experience  or  the  content  which  gives  the  lie 
to  the  impressiveness  of  the  other  factors.  The 
semblance  of  reality  produced  in  pictures  and  on 
the  stage  is  to  be  classed  as  pseudo-illusion.  The 
familiar  geometrical  illusions,  on  the  other  hand,  are 
true  illusions  in  most  cases,  for  the  semblance  has 
all  the  characteristics  of  true  perception-content, 
in  spite  of  the  fact  that  we  know  it  is  not.  We  have 
to  do  here  with  a  percept  and  an  additional  con- 
cept which  do  not  fuse  or  unite.1 

1  Hallucinatory  perceptions  must  be  distinguished  from 
subjective  sensations,  secondary  sensations,  and  after  images, 


PERCEPTION  205 

3.  The  Determination  of  Perceptual  Truth  and  Falsity 

The  discussion  of  illusion  brings  us  to  the  con- 
sideration of  the  criterion  of  truth  in  perception. 
Here  we  find  two  questions.  First:  When,  and 
in  how  far,  is  a  perception  true?  and  second:  How 
do  we  decide  whether  a  sensation  is  true  or  suffi- 
ciently near  the  truth?  As  a  matter  of  fact,  the 
grounds  on  which  we  decide  practically  the  truth 
of  a  perception  are  by  no  means  those  which  would 
be  assumed  for  the  philosophical  justification  of 
the  decision.  The  statement  of  the  grounds  on 
which  we  actually  judge  the  validity  of  a  perception 
does  not  cover  the  grounds  on  which  a  thoroughly 
adequate  determination  could  be  based. 

There  are  two  practical  tests  of  truth  and  falsity. 
The  first  may  be  called  the  social  test.  If  my  per- 
ception is  illusory  or  hallucinatory,  it  is  in  most 
cases  shared  by  no  one  else,  and,  conversely,  if  it  is 
shared  by  no  one  else  it  is  an  illusion  or  hallucina- 
tion. If,  for  example,  you  see  a  translucent  hand 
beckoning  from  the  door-way,  and  others  in  the 

and  from  the  phenomena  in  certain  pathological  cases  where, 
for  example,  the  smell  of  a  certain  odor  is  persistently  present 
to  consciousness,  without  the  normal  stimulation.  All  these 
cases  are  of  present  sensations  due  to  definite  sensory  processes 
in  the  sense  mechanism. 


206  A   SYSTEM   OF   PSYCHOLOGY 

same  room  see  nothing  of  the  kind,  you  know  that 
you  have  an  hallucination,  and  if  you  are  wise  will 
consult  a  competent  physician.  If  you  hear  some 
one  talking,  whereas  other  persons  in  the  same  room 
hear  only  the  trickling  of  water  from  a  leaky  fau- 
cet, you  conclude  that  you  were  mistaken  in  your 
perception. 

The  social  test  is  not  thoroughly  trustworthy. 
Frequently  your  perceptions  are  right  and  those  of 
your  companions  wrong.  The  obstinacy  of  one 
man  in  insisting  that  he  hears  the  crying  of  a  child, 
when  the  others  are  equally  confident  that  the 
sound  is  the  moaning  of  the  wind  in  the  trees, 
saves  the  child's  life.  It  is  possible,  also,  for  a 
number  of  people  to  be  simultaneously  illuded,  as 
a  number  of  "authentic"  ghost  stories  show.  Per- 
sons of  the  same  general  type  and  training  placed 
in  similar  circumstances  will  perceive  in  much  the 
same  way,  and  there  is  nothing  surprising  in  the 
fact  that  a  number  of  people  will  bring  up 
wrong  concepts  of  approximately  the  same  sort,  if 
the  conditions  are  about  the  same  for  all.  For 
example,  if  several  persons  are  expecting  to  see  a 
ghost,  that  is,  if  the  appropriate  concepts  and  images 
have  been  recently  and  vividly  attended  to,  the 
sensational  data  which  suffices  to  revive  and  unite 


PERCEPTION  207 

with  the  ghost-concept  of  one  may  suffice  for  the 
others. 

The  important  practical  test  is  your  own  further 
experience.  If  the  pin  you  see  on  the  floor  can  be 
picked  up,  and  stuck  into  something,  it  is  still  con- 
sidered as  a  pin.  But  if  it  fails  to  give  all  the  sen- 
sations (visual,  tactual,  etc.,)  expected  from  a  pin, 
you  conclude  that  your  first  perception  was  wrong. 
If  the  man  you  take  for  an  acquaintance  does  not 
respond  to  your  words  in  the  way  you  expect,  you 
conclude  that  after  all  he  is  some  one  else.  And 
so  on.  A  large  part  of  the  perceptions  of  our  ex- 
perience are  proved  inadequate  by  the  further 
transformations  of  the  content,  and  are  revised 
accordingly. 

The  philosophical  question  as  to  the  real  nature 
of  truth  arises  from  the  consideration  of  the  possi- 
bility that  we  may  be  more  or  less  deluded  in  our 
daily  life  without  becoming  aware  of  it.  So  many 
times  we  act  on  a  misconception,  and  yet  our  action 
fits  the  case  sufficiently  well,  that  we  wonder  if  any 
of  our  tests  give  us  anything  really  fundamental. 
One  school  of  modern  philosophy  insists  that  any- 
thing is  true  in  so  far  as  it  works,  and  no  farther; 
that  truth  is  just  the  fact  of  standing  the  practical 
test.     An    older   conclusion    is    that   a    perception 


208  A   SYSTEM   OF   PSYCHOLOGY 

may  be  true  or  false  quite  regardless  of  my  action 
on  it;  that  when  I  perceive  a  bottle  in  the  road  in 
the  moonlight,  it  either  is  or  is  not  a  bottle,  even 
if  I  do  not  get  off  my  horse  to  investigate  it.  But 
no  one  has  been  able  to  propose  a  really  satisfactory 
explanation  of  the  nature  of  truth. 

4.  The  Causes  of  Illusion 

The  immediate  cause  of  illusion  is  not  different 
from  that  of  normal  or  correct  perception.  The 
imaginative  content  which  is  in  the  one  case  in- 
adequate, and  in  the  other  case  adequate  addition 
to  the  intuited  factors,  is  in  either  case  revived 
through  association.  It  is  not  necessary  that  the 
reproduced  content  should  be  previously  associated 
with  the  directly  presented  content  in  the  perception; 
it  may  be  called  up  through  an  associative  linking 
with  some  other  content  factor  in  consciousness. 
Thus,  you  take  the  shadow  by  the  roadside  for  a 
robber,  not  because  that  particular  impression  of 
light  and  shade  is  essentially  connected  with  the 
figure  of  a  man,  but  because  your  consciousness  is 
already  filled  with  imagination  of  brigands  and 
hold-ups.  In  commoner  cases,  you  misread  a 
printed  word,  or  mistake  spoken  words  because 
something  you  have  just  read,  or  heard,  or  thought 


PERCEPTION  20(J 

of  is  associated  with  the  idea  corresponding  to  the 
misreading  or  mishearing. 

In  normal  perception,  you  make  out  the  cold 
cylinder  you  grasp  in  the  darkness  of  the  garden 
to  be  the  hose  because  you  imagined  it  to  be  there 
(or  possibly  you  conceived  it  as  there)  before  you 
touched  it;  if  you  did  not,  it  gave  you  a  shock,  and 
the  perception  came  more  slowly  after  additional 
factors  had  been  experienced.  Waiting  for  the 
train,  the  distant  whistle  is  easily  recognized,  when 
otherwise  it  would  have  passed  for  one  of  the  feat- 
ures of  the  storm  roaring  about  vou.  In  reading, 
the  words  are  recognized  by  the  appearance  which 
you  sense  in  an  inadequate  way,  assisted  by  the 
images  excited  by  the  preceding  words  and  sen- 
tences. 

Association  directly  between  the  reproduced 
factor  and  the  intuited  factor  of  the  perception  con- 
tent is  an  important  feature  in  the  greater  part  of 
our  perceptual  life.  Experience  is  a  constant  suc- 
cession of  perceptions  whose  contents  are  unex- 
pected until  they  occur,  and  the  imaginative  parts 
whereof  are  not  contributed  from  the  just-preced- 
ing, or  contemporaneous  contents.  The  seen  or 
otherwise  intuited  impressions  call  up  the  imagery 
associated  with  them  from  the  past,  and  it  may  be 


210  A   SYSTEM   OF   PSYCHOLOGY 

adequate  to  the  occasion,  or  it  may  not.  The  notes 
of  the  flute  which  fall  upon  your  ear  from  the  next 
house  are  perceived  as  the  sound  of  that  empty- 
toned  instrument  although  you  had  not  been  think- 
ing of  flute  or  flute-tone  until  these  notes  smote 
your  ear.  The  spider  crawling  on  your  knee  may 
have  been  entirely  unexpected  until  he  met  your 
eye,  and  yet  you  perceived  him  immediately.  The 
sound  of  some  one  shutting  the  door,  which  turns 
out  finally  to  have  been  the  creaking  of  your  chair, 
was  not  perceived  wrongly  because  your  conscious- 
ness was  filled  with  the  idea  of  some  one  entering 
the  room,  but  because  that  particular  sound  was 
associated  in  your  past  experience  with  the  other 
sensations  from  shutting  a  door. 

In  determining  the  definite  perception  based  on 
a  given  intuited  content,  the  factors  we  have  earlier 
described  as  governing  the  "strength"  of  associa- 
tion and  likelihood  of  recall  play  a  large  part.  If  a 
certain  sense-content  is  strongly  associated  with 
certain  other  factors,  either  through  repeated  ex- 
perience of  them  in  conjunction,  or  because  of  the 
recency  or  impressiveness  of  such  an  experience, 
that  sense-content  will  tend  to  call  up  those  factors 
regardless  of  whether  they  are  the  right  or  wrong 
things  at  the  time.     Moreover,  the  mere  recency, 


PERCEPTION  211 

frequency,  and  vividness  of  past  experience  of  a 
given  content  which  is  at  all  capable  of  assimilation 
to  intuited  content,  increase  the  probability  of  its 
being  revived  by  the  intuited  content,  in  accordance 
with  the  principles  of  retention  and  recall.  The  co- 
operation of  associations  is  also  of  importance  in 
many  cases;  if  you  notice  the  peculiar  noise,  and 
at  the  same  time  notice  the  movement  of  your  body 
in  your  chair,  you  will  be  less  apt  to  perceive  the 
opening  of  the  door,  although  the  sound  alone  might 
have  called  up  that  illusory  perception. 

Fine  discrimination  of  sensations  favors  correct 
perception.  The  creaking  of  the  chair  was  not 
precisely  like  the  sound  made  by  the  opening  of  the 
door,  so  that  the  presence  or  absence  of  the  illu- 
sion depends,  in  part,  on  the  delicacy  with  which 
auditory  differences  are  apprehended.  In  so  far 
as  sensory  complexes  seem  alike  they  tend  to  call 
up  the  same  associated  factors,  because  the  features 
of  the  contents  which  are  noticed  are  associated 
with  these  factors;  and  in  as  far  as  the  contents  are 
discriminated,  that  is,  in  as  far  as  other  factors  than 
the  common  ones  are  noticed,  they  tend  to  call  up 
their  special  associates. 


212  A    SYSTEM   OF   PSYCHOLOGY 

5.  Space  Perception 

In  the  analysis  of  perceived  space  we  find  one  of 
our  knottiest,  but  most  interesting,  problems.  The 
history  of  philosophy  includes  much  discussion  of 
the  question  whether  space  is  an  actual  external 
reality  (the  a  posteriori  theory),  or  whether  it  is 
something  mental — a  "form"  in  our  minds,  sup- 
erposed on  the  world  in  perceiving  it — (the  a  priori 
theory).  The  discussion  of  this  question  has  really 
little  to  do  with  experience  or  its  content,  being 
based  on  conventional  definitions  of  "mind" 
"external  world"  and  other  terms,  much  as  the 
moves  in  a  game  are  determined  by  rules;  but  it 
has  had  an  unfortunate  influence  on  attempts  at 
psychological  analysis. 

We  must  start  from  the  fact  that  there  is  in  our 
perceived  content  a  factor  which  is  practically  the 
"space"  of  common  parlance  (not  the  "space"  of 
the  mathematician  or  metaphysician),  and  attempt 
to  analyze  this  factor. 

The  line  of  opposition  has  been  drawn  in  the 
past  between  the  "nativistic"  and  the  "genetic" 
theories  of  space  perception.  In  large  part,  the 
controversy  between  those  holding  these  two  views 
has  been  an  unwitting  discussion  of  the  a  priori- 


PERCEPTION  213 

a  posteriori  question,  complicated  by  the  question 
whether  we  have  to  learn,  as  individuals,  to  perceive 
space,  or  whether  we  perceive  it  instinctively.  In- 
volved in  the  controversy  is  the  still  further  ques- 
tion whether  space  as  perceived  is  sui  generis,  or 
whether  it  is  constructed  in  some  way  out  of  ele- 
ments which  are  non-spatial.  The  genetic  view 
insists  that  we  learn  to  perceive  space,  and  is  usually 
a  prioristic:  the  nativistic  view  holds  to  instinctive 
space  perception,  and  may  take  either  the  a  priori 
or  the  a  posteriori  tack.  The  apriorists,  of  course, 
believe  space  to  be  sui  generis;  the  aposteriorists, 
whether  nativistic  or  genetic,  may  take  either  side 
of  this  latter  question. 

While  our  business  here  is  primarily  the  analysis 
of  the  space-content,  keeping  clear  of  the  meta- 
physical problems  as  far  as  possible,  we  shall  not 
hesitate  to  assume  that  we  as  individuals  learn  by 
experience  to  perceive  space  in  its  detailed  form, 
although  a  part  of  our  perceptive  ability  is  native 
or  instinctive.  This,  however,  is  nothing  but  as- 
sumption, and  our  suggestions  as  to  the  probable 
development  of  space-content  must  be  understood 
in  the  light  of  that  fact. 

The  characteristic  thing  about  the  space-world 
is  that  everything  in  it  stands  in  definite  and  peculiar 


214  A    SYSTEM   OF   PSYCHOLOGY 

relations  to  everything  else  therein;  relations  which 
are  analogous  to  some  found  outside  of  the  space- 
world,  but  which  are  characteristically  different 
from  them.  These  space  relations  we  recognize 
when  we  refer  to  distance,  direction,  contiguity, 
intervening  objects,  and  other  characteristic  features 
of  the  spacial  factor  of  our  content. 

In  addition,  space  depends  on  the  relation  of 
magnitude,  which  is  found  also  in  non-spatial  con- 
tent, and  likewise  upon  the  universal  relations  of 
similarity,  difference,  etc.;  but  these  are  not,  prop- 
erly speaking,  factors  in  space. 

Space  relations  can  be  intuited  only  as  founded 
upon  the  extensity-character  of  sensation.  Whether, 
having  been  perceived,  they  may  be  imagined — 
may  form  part  of  a  conception — without  the  imaged 
sensation,  is  another,  and  questionable,  matter. 
Our  own  opinion  is  that  when  space  is  strictly  con- 
ceived it  loses  its  true  content-character,  and  be- 
comes merely  a  mathematical  system  of  relations 
which  is  marked  by  a  correspondence  to  the  space 
of  perception  and  imagination. 

The  difference  between  extensity  and  extension; 
between  the  mere  sensational  volume  and  space,  is 
this:  as  soon  as  you  begin  to  discriminate  extensive 


PERCEPTION  215 

parts  within  a  sensation,  or  mass  of  sensation,  you 
have  space.  The  perception  of  the  extensity  as 
divided;  as  having  one  part  set  off  against  another 
part — the  perception  of  extensity  in  relation — is 
the  perception  of  extension  or  space. 

In  gustatory  and  olfactory  sensation  we  have  no 
distinction  of  extensive  parts,  and  in  consequence 
no  gustatory  or  olfactory  space.  These  sensations 
may  be  more  or  less  massive  or  extensive,  but  that 
is  all.  The  same  is  true  of  sounds;  the  volume  of 
a  tone  may  change,  but  there  is  no  space-character 
to  the  tones  because  there  is  no  relation  of  extensive 
parts  of  any  tone,  but  simply  a  relation  of  extensities 
of  different  tones.  We  may  say,  with  great  proba- 
bility of  correctness,  that  if  we  were  restricted  to 
these  sensations  there  would  be  no  space  in  the  con- 
tent of  our  perceptions. 

Vision  and  touch  supply  the  necessary  conditions 
for  the  perception  of  a  space-world.  In  these  senses 
we  have  extensive  magnitudes  which  are  not  homo- 
geneous, but  which  are  differentiated  by  local  signs. 
One  extensive  portion  of  sensation,  (if  of  sufficient 
magnitude),  is  immediately  different  from  other  por- 
tions, and  hence  we  may  believe  that  an  animal  hav- 
ing only  one  of  these  sorts  of  sensation,  or  any  sort 
of  sensation  in  which  extensity  and  local  signs  are 


21G  A    SYSTEM   OF    PSYCHOLOGY 

developed,  perceives  space,  although  the  space 
may  not  be  very  complex.1 

The  fundamental  spatial  relation  seems  to  be 
betweenness.  This  differs  essentially  from  the  mere 
intermediacy  of  other  continua,  although  we  com- 
monly represent  all  sorts  of  intermediacy  in  the 
spatial  terms;  as,  for  instance,  a  series  of  values  by 
points  on  a  straight  line.  The  perception  of  be- 
tweenness in  space  may  depend  on  the  perception 
of  time;  that  is,  when  an  object  moves  over  the 
skin  or  retina  it  occupies  a  certain  position  between 
the  moments  at  which  it  occupies  other  positions; 
and  by  repetition  of  these  experiences  the  spatial 
betweenness  of  the  various  points  is  brought  to 
perception.  Yet  it  is  not  at  all  certain  that  the  spa- 
tial betweenness  may  not  be  perceived  as  directly 
as  the  temporal. 

The  perception  of  the  intermediacy  of  local  signs 
in  an  extensity  continuum  furnishes  the  primary 
datum  of  space.  The  relation  of  direction  may  be 
reducible  to  these  factors  plus  the  implication  of 
motion;  but  this  is  a  mere  conjecture.  The  oc- 
currence of  the  same  local  sign  in  two  different  series, 
as  a  stimulus  moves  in  actually  different  directions 

1  For  the  "musical"  ear  the  series  of  pitches  may  therefore 
form  a  rudimentary  space-system. 


PERCEPTION  217 

over  the  sensitive  surface,  may  be  the  first  clew  to 
difference  of  direction. 

Distance  is  primarily  the  amount  of  difference 
in  local  sign  between  two  points;  this  corresponds 
roughly  to  the  least  number  of  local  sign  differences 
discriminable  between  the  two  points.  You  will 
find  for  example,  on  the  skin,  that  two  points  appear 
separated  by  an  interval  approximately  propor- 
tional to  the  number  of  different  points  discrimin- 
able in  the  straight  line  between  them.  This  is 
why  the  points  of  a  pair  of  compasses  or  scissors  a 
quarter  of  an  inch  apart  appear  more  widely  sep- 
arated on  the  finger-tip  than  on  the  arm,  and  still 
more  widely  separated  on  the  tip  of  the  tongue. 
Of  course,  if  no  points  are  discriminable  between 
two  given  points,  they  will  be  perceived  as  one 
point.1 

So  far  we  have  considered  only  the  factors  which 
enter  into  space  of  two  dimensions,  that  is,  of  sur- 
face. An  animal  endowed  with  touch  or  sight,  or 
both,  but  with  no  sensation  of  movement,  would 

1  An  interesting  experiment  may  be  made  by  drawing  the 
points  of  a  pair  of  compasses  across  the  face  from  side  to  side, 
allowing  one  point  to  pass  above  and  the  other  below  the 
mouth,  and  observing  the  apparent  variation  in  the  separation 
of  the  points  when  the  distance  between  them  is  constant. 
Also,  try  drawing  the  points  abreast  down  the  arm,  or  down 
the  lee  from  knee  to  ankle. 


218  A   SYSTEM  OF   PSYCHOLOGY 

have  experience  of  a  space  in  which  sensations  ap- 
peared, moved  about,  and  vanished;  but  the  re- 
moval of  the  stimuli  from  the  skin  would  simply 
cause  the  sensation  to  be  unperceived,  and  stimuli 
at  greater  or  less  distances  from  the  eye  would  sim- 
ply give  sensations  of  less  or  greater  area.  The 
animal  with  touch  and  sight  would  probably  per- 
ceive two  spaces,  for  the  chance  that  he  would  iden- 
tify his  tactual  and  visual  surfaces  is  slight.  But, 
given  the  power  of  sensations  from  the  movements 
of  the  sense-organs  and  members  of  the  body,  and 
unified  space  perception  in  three  dimensions  be- 
comes possible. 

It  is  scarcely  probable  that  muscular  sensation 
by  itself  can  give  space-content.  The  only  between- 
ness  of  such  sensation  is  the  temporal  betweenness, 
and  its  function  in  the  production  of  space-content 
can  be  only  secondary.  But  it  does  help  to  de- 
velop our  space-content  in  a  very  important  way, 
the  outline  of  which  is  probably  as  follows.  By 
moving  one  member  (as  the  finger),  over  another 
member  (as  the  hand),  we  acquire  the  connection  of 
the  temporal  series  of  muscular  sensations  with  the 
motion  or  series  of  positions  in  tactual  space  on  the 
hand,  and  the  continuous  stimulation  of  one  spot 
on  the  finger.     By  moving  the  finger  over  some  ex- 


PERCEPTION  219 

ternal  object  we  obtain  the  same  series  of  muscular 
sensations,  with  the  same  sort  of  stimulation  of  the 
finger.  The  result  is  the  conception  of  a  surface 
over  which  the  finger  moves  in  the  same  way  as  it 
moves  over  the  hand;  the  temporal  series  of  mus- 
cular sensations  having  become  associated  with  a 
series  of  positions  in  space,  (tactual  sensation  ex- 
tension), muscular  series  which  do  not  rouse  the 
tactual  series  suggest  series  of  positions  in  addition  to 
those  in  the  tactual  field;  hence  space  is  immensely 
multiplied  in  extent.  At  the  same  time,  since  the 
same  series  of  muscular  sensations  may  condition 
a  movement  in  tactual  space  and  a  movement  in 
visual  space,  and  the  connection  of  two  such  series 
is  invariable,  the  two  are  identified  as  a  mere  matter 
of  mental  economy;  that  is  to  say,  tactual  space  is 
identified  with  visual  space. 

If  the  above  were  the  whole  story,  space  as  per- 
ceived would  still  be  a  matter  of  surface  only.  The 
feature  of  tactual-muscular  perception  which  brings 
"depth"  into  space  is  this:  a  series  of  muscular 
sensations  not  accompanied  by  a  series  of  tactual 
sensations  (the  finger  moving  through  the  air)  may 
end  in  conjunction  with  a  definite  tactual  sensation, 
and  in  fact  we  can  put  no  limit  to  the  number  of 
different  series  which  may  terminate  in  conjunc- 


220  A    SYSTEM   OF   PSYCHOLOGY 

tion  with  a  sensation  of  practically  any  local  sign. 
Here  we  have  the  primary  factor  in  tri-dimensional 
space;  series  of  positions,  of  which  one  or  at  most 
two  lie  in  the  given  surface.  Finding  no  definite 
limit  to  the  number  of  series  terminating  at  any 
position,  the  step  to  the  conception  of  an  infinite 
number  is  easy.  In  visual  perception  we  have 
similar  conditions,  in  that  certain  series  of  muscular 
sensations  correspond  to  series  of  positions  in  the 
visual  field,  while  certain  other  series  correspond 
to  a  single  position. 

It  is  not  necessary  to  assume  that  the  individual 
has  to  go  through  the  stages  from  "  blooming  buz- 
zing confusion"  through  two-dimensional  space  per- 
ception to  tri-dimensional.  It  is  not  necessary  to 
suppose  that  the  infant's  perceived  space  is  other 
than  tri-dimensional  from  the  first.  But  without 
doubt  the  space  relations  are  at  first  rather  vague 
and  simple,  until  the  discrimination  of  local  signs, 
and  their  connection  with  muscular  sensations 
clears  up  and  amplifies  the  content  spatially  as  the 
child's  motor  processes  develop  and  receive  exer- 
cise. If,  however,  the  individual  does  not  perceive 
space  instinctively,  it  seems  quite  possible  for  the  fac- 
tors mentioned  to  bring  the  necessary  relations  to  his 
consciousness,  and  build  up  the  percept  of  extension. 


PERCEPTION  221 

We  may  describe  a  few  experiments  illustrating 
the  co-ordination  of  visual  and  tactual  space  with 
muscular  sensations.  Hold  before  one  eye  a  prism 
with  large  side,  but  narrow  base,  turning  the  base 
either  to  right  or  to  left,  and  closing  or  covering  the 
other  eye.  Better  still,  have  a  prism  or  a  pair  of 
prisms  set  in  a  spectacle  frame,  thus  permitting  the 
use  of  both  eyes,  and  supporting  them  while  leav- 
ing the  hand  free.  On  looking  through  the  prism 
at  any  small  object  placed  before  you  on  the  bare 
table,  the  object  will  in  appearance  be  displaced  to 
one  side.  Keeping  your  hand  out  of  sight  by  your 
side  until  the  moment  of  trial,  make  a  rapid  stab  at 
the  object  with  you  forefinger.  You  will  find  that 
the  finger  strikes  to  one  side  of  the  goal.  Keep  on 
trying,  and,  in  the  course  of  a  few  minutes,  you 
will  find  yourself  able  to  hit  the  mark  fairly  well. 
Now  remove  the  prism  from  the  eye  and  repeat 
the  trials,  and  you  will  find  that  you  now  make 
misses  on  the  other  side  of  the  target,  and  require 
some  practice  to  get  back  to  your  normal  co-ordina- 
tion again. 

Suppose,  looking  through  the  prism,  you  touch 
your  hand  or  arm  with  a  pencil;  or,  better  still, 
have  some  one  else  do  the  touching.  The  tactual 
and    the  visual  spaces  no  longer   seem  the  same, 


222  A    SYSTEM   OF   PSYCHOLOGY 

but  a  little  practice  will  bring  them  together  as 
before. 

An  interesting  experiment,  named  after  the 
philosopher  who  gave  the  earliest  extant  descrip- 
tion of  it,  "Aristotle's  Experiment,"  has  been  re- 
ferred to  in  2  of  Chapter  IX.  If  the  first  and  second 
fingers  are  crossed  and  the  Y  so  formed  is  rubbed 
in  the  crotch  with  a  pencil  or  rod,  the  rod  feels 
double.  The  effect  is  still  more  surprising  if  the 
crotch  of  the  crossed  fingers  is  touched  with  the  tip 
of  the  tongue  or  point  of  the  nose;  you  can  hardly 
fail  to  have  the  distinct  perception  of  a  forked 
tongue  or  bifurcated  nose.  But  even  this  illusion 
can  be  destroyed  by  continued  stimulation  under 
visual  control. 

Although  space  relations  may  be  in  the  first  in- 
stances— and  later  also — intuited  just  as  are  sensa- 
tions, they  are  in  a  great  part  of  our  perceptual  ex- 
perience purely  ideal;  they  are  reproduced  in  the 
content  through  their  association  with  intuited  or 
reproduced  sensory  data.  This  is  true,  at  any  rate, 
in  the  visual  perception  of  space,  and  there  we  know 
rather  definitely  what  the  factors  are  which  are 
associated  with  the  relations. 

Direction,  that  is,  the  angular  estimation  of  space 
position  with  regard  to  the  body  or  eye  as  a  centre, 


PERCEPTION  223 

is  indicated  by  retinal  local  sign,  in  conjunction  with 
the  muscular  sensations  coming  from  the  ocular 
apparatus  and  the  muscles  of  the  body,  especially 
the  neck.  Simultaneous  stimulation  of  different 
spots  of  the  retina  gives  localization  in  different 
directions,  as  do  successive  stimulations  of  one  spot 
if  certain  muscular  sensations  intervene.  By  the 
specific  muscular  sensations  intervening  between 
the  successive  occupancy  of  one  spot  by  two  stimuli 
the  angle  between  the  two  is  estimated;  that  is, 
the  relative  direction  of  the  two  from  the  eye. 

Distance  from  the  eye  is  indicated  by  a  number 
of  signs,  which  may  be  effective  singly  or  in  co- 
operation. These  factors  are  (1)  light  and  shade 
(chiaro-oscuro),  (2)  definition  and  color  (aerial  per- 
spective), (3)  size  (linear  perspective),  (4)  angular 
perspective,  (5)  convergence  and  accommodation, 
(G)  binocular  disparity,  and  (7)  parallax. 

(1)  Objects  in  advance  of  others  throw  shadows 
across  them,  the  direction  of  the  shadows  depending 
on  the  direction  of  the  source  of  light.  Often  the 
depth  of  shadow  corresponds  to  the  degree  of  re- 
lief. A  curious  effect  may  be  obtained  from  an  in- 
taglio, obliquely  lighted ;  it  will  appear  at  times  to  be 
a  cameo,  with  the  light  coming  from  the  opposite 
side.     A  little  study  will  show  you  that  the  lights 


224  A    SYSTEM   OF   PSYCHOLOGY 

and  shadows  of  an  intaglio  do  correspond  approxi- 
mately with  those  of  a  cameo,  if  the  two  are  lighted 
obliquely  from  opposite  sides.  How  large  a  part 
chiaro-oscuro  plays  in  visual  perception  may  be  il- 
lustrated by  making  a  negative  print  of  a  portrait, 
and  comparing  it  with  the  positive  print.  The  re- 
versal of  light  and  shade  makes  the  picture  surpris- 
ingly different. 

(2)  Objects  at  a  considerable  distance  from  the 
eye  are  blurred  through  the  irregular  refraction  of 
the  air,  and  they  likewise  are  tinged  with  color  by 
the  atmosphere.  "Dim  distance"  and  "purple 
peaks,"  indicate  the  practical  importance  of  this 
factor.  The  blurring  of  distant  objects  is  easily 
noted  in  nature,  and  its  representation  is  frequent 
in  paintings.  The  absence  of  the  customary  tint- 
ing distortion,  as  in  the  Rockies,  where  the  air  is 
fairly  pure  and  homogeneous,  gives  rise  to  ludicrous 
mistakes  on  the  part  of  those  unused  to  such  con- 
ditions. The  author  once  heard  a  tourist  insist  that 
he  could  easily  walk  in  an  hour  to  the  base  of  the 
mountain  range  at  which  we  were  gazing;  the  range 
being  really  more  than  forty  miles  distant. 

(3)  As  an  object  recedes  from  the  eye  its  retinal 
image  becomes  smaller;  all  lines  connecting  char- 
acteristic points  in  the  image  become  shorter.     It 


PERCEPTION  225 

follows,  that  if  we  know  what  size  the  object  would 
appear  when  near,  we  have  in  this  some  information 
as  to  the  distance  from  the  eye  at  any  time. 

(4)  The  form  of  an  angle  gives  some  information 
as  to  the  relative  distance  from  the  eye  of  parts  of 
the  surface  bounded  by  the  lines  composing  it,  pro- 
vided we  know  what  the  angle  is  really — that  is, 
know  its  appearance  from  a  certain  position.  A 
rectangular  table  top,  viewed  from  a  point  not  in  a 
plane  passing  through  the  centre  of  the  rectangle  and 
perpendicular  to  one  side,  appears  a  rhomboid,  and 
conversely,  to  represent  a  rectangular  surface  looked 
at  obliquely  a  painter  employs  a  rhomboidal  figure. 

(5)  The  eyes  must  turn  inward  more  strongly 
to  look  at  a  near  object  than  at  a  far  object.  Like- 
wise, they  must  accommodate,  that  is,  change  the 
shape  of  the  lens  by  muscular  action  for  the  near 
object.  The  sensations  of  these  muscular  adjust- 
ments give  immediate  information  as  to  relative 
distances  of  objects  fixated.  Hold  up  your  pencil 
a  foot  or  so  before  your  eyes  and  fixate  alternately 
the  point  and  a  spot  on  the  wall  in  line  with  it; 
you  will  find  that  the  convergence  and  accommoda- 
tion sensations  are  quite  intense. 

(6)  Since  the  two  eyes  look  at  the  presented  scene 
from  two  different  points  of  view,  their  images  do 


226  A    SYSTEM   OF   PSYCHOLOGY 

not  exactly  agree.  This  disparity  of  the  images  of 
the  two  eyes  is  turned  to  practical  account  in  the 
stereoscope,  which  presents  two  slightly  different 
pictures  to  the  eyes.  Since  the  pictures  are  origi- 
nally taken  by  a  camera  with  two  lenses,  from  two 
points  of  view  corresponding  to  those  of  the  eyes,  the 
stereoscope  reproduces  the  binocular  disparity  of  a 
natural  scene.  The  depth  given  by  a  stereoscope 
view  is  a  demonstration  of  the  importance  of  the 
binocular  disparity  sign  in  visual  perception. 

(7)  When  you  move  your  head  laterally,  the  view 
before  you  changes  slightly.  An  object  may  be  hid- 
den behind  another  when  the  head  is  in  one  posi- 
tion, and  emerge  when  the  head  moves  far  enough 
to  one  side.  An  object  not  hidden  by  a  nearer 
one  apparently  moves  closer  to  or  farther  away 
from  it.  The  relative  amount  of  parallactic  dis- 
placement indicates  the  relative  distances  of  the 
objects. 

Auditory  sensations  are  localized  in  the  space 
perceived  through  the  visual,  tactual,  and  muscular 
mechanisms,  but  not  localized  accurately.  We  can 
usually  tell  the  side  from  which  a  sound  comes 
by  the  difference  in  intensity  for  the  two  ears;  and 
we  may  make  a  lucky  guess  as  to  its  general  direc- 
tion, especially  if  allowed  to  turn  the  head    while 


PERCEPTION  227 

listening.1  In  general,  however,  we  attach  the 
sound  to  the  seen,  felt,  or  imagined  object  which 
seems  an  adequate  cause  of  the  sound;  hence  the 
success  of  the  ventriloquist.  There  can  be  no 
direct  spatial  reference  of  auditory  sensation;  a  state 
of  affairs  which  is  puzzling  until  we  reflect  that 
the  actual  direction  from  which  the  sound  ap- 
proaches can  make  no  difference  in  the  local  sign 
of  the  sensation. 

6.  The  Perception  of  Things 
The  reader  has  doubtless  been  somewhat  sceptical 
during  our  exposition  of  the  content  of  perception. 
Sensations,  relations — these  are  all  very  well,  and 
there  is  no  doubt  that  we  do  perceive  them,  but  the 
important  features  of  the  world  about  us  do  not 
seem  to  be  exhausted  by  this  simple  list.  We  per- 
ceive things,  in  which  certain  qualities  inhere,  and 
although  one  may  be  persuaded  that  the  qualities 
are  sensations,  and  that  the  things  stand  in  percep- 
tible relations  to  one  another,  he  can  only  with 
difficulty  be  convinced  of  the  necessity  of  abandon- 

1  Experiments  seem  to  demonstrate  that  under  certain 
favorable  conditions  the  difference  in  phase  of  the  sound- 
waves affecting  the  two  ears  (when  one  ear  is  nearer  the  source 
of  sound),  may  assist  in  the  determination  of  the  direction 
from  which  the  sound  comes.  In  this  case  the  subject  is,  of 
course,  unaware  of  the  difference  itself. 


228  A   SYSTEM   OF   PSYCHOLOGY 

ing  the  things  themselves.  Nor  would  we  desire  to 
convince  hirn  of  such  necessity.  We  have  simply 
labored  to  show  the  student  of  what  stuff  the  things 
he  perceives  are  made,  without  attempting  to  prej- 
udice his  view  as  to  whether  this  world  of  things 
is  entirely  within  himself,  as  Idealism  and  Material- 
ism teach,  or  whether  the  conditions  are  as  common- 
sense  assumes  them  to  be. 

The  nature  of  perceived  objectivity  offers  a  prob- 
lem for  analysis  which  is  simple  as  compared  with 
some  of  the  other  problems  of  content.  Assuming 
the  perception  of  space,  we  find  the  fundamental 
feature  of  thinghood  in  the  location  of  one  sensory 
quality  or  group  of  qualities  in  the  same  space  with 
another.  It  is  very  probable  that  an  animal  re- 
stricted to  one  mode  of  sense  would  not  be  able  to 
perceive  "  things "  as  we  do.  He  might  perceive 
spatial  relations,  but  they  would  be  comparable 
to  the  spatial  relations  we  perceive  in  a  picture. 
Allow  him,  however,  the  opportunity  to  identify 
visual  sensations  with  a  definite  portion  of  tactual 
space,  or  vice  versa,  or  to  identify  muscular  sensa- 
tions with  parts  of  either  space,  and  all  the  essen- 
tial features  of  perceived  objectivity  are  present. 
The  "thing"  which  we  perceive  is  just  the  coinci- 
dence of  sensations  of  diverse  modes  in  definite 


PERCEPTION  229 

space  relations,  and  involved  in  the  manifold  of 
other  relations  component  in  content.  When  Ave 
become  metaphysical,  we  invent  something  called 
"substance"  or  "matter"  to  act  as  a  mystic  cause 
for  this  coincidence,  but  if  we  did  not  have  the 
experience  of  thinghood,  substance  would  never 
have  been  invented.  The  psychological  problems 
involved  in  the  construction  of  such  a  concept  as 
that  of  substance,  a  concept  which  in  itself  is  an 
experienced  content,  but  which  represents  or  refers 
to  the  transcending  of  experience,  introduce  no 
new  difficulties,  but  belong  to  the  mountains  of 
details  upon  which  we  cannot  touch  in  this  outline. 

7.  The  Perception  of  Time 

In  the  field  of  time  perception  we  find  again  the 
division  between  the  apriorists  and  the  aposterior- 
ists,  but  no  real  genetic  theory  of  time  has  been 
constructed,  nor  has  any  one  proposed  a  plan  of 
time-content  reduced  to  non-temporal  factors.  As 
in  the  case  of  space,  we  may  assume  with  proba- 
bility that  we  learn,  in  part  at  least,  to  perceive 
time,  but  this  is  hardly  more  than  hypothesis. 

Philosophers  of  the  past  were  accustomed  to 
ascribe  space  to  "outer  perception,"  and  time  to 
"inner  perception."  As  these  terms  are  now  in- 
terpreted they  meant  sense  perception  and  thought 


230  A    SYSTEM   OF   PSYCHOLOGY 

(imagination,  including  memory),  respectively,  but 
this  interpretation  makes  the  distinction  as  regards 
space  and  time  meaningless.  We  can  imagine  con- 
tent which  involves  spatial  relations  just  as  well  as 
we  can  perceive  it,  and  we  can  certainly  perceive 
time.  It  is  quite  probable  that  these  older  phi- 
losophers had  a  more  subtle  meaning  than  their 
words  adequately  express  to  us;  but  it  is  not  our 
task  at  present  to  search  for  this. 

The  chief  points  of  temporal  content,  upon  which 
we  shall  touch  lightly,  are  (1)  passing  time  and 
change,  (2)  temporal  extent,  and  (3)  temporal  dis- 
tinction and  identification. 

(1)  The  immediate  content,  which  is  called  pass- 
ing time,  is  change  in  the  content  of  consciousness. 
We  do  not  mean  to  say  that  time  is  built  up  out  of 
change,  but  that  change  as  directly  perceived,  in 
abstraction  from  any  critical  points  in  the  series  of 
changes,  is  the  passing  time.  By  critical  points, 
we  mean  conditions  of  content  from  which  the 
change  is  thought  to  occur,  or  toward  which  it  is 
thought  to  be  directed.  Thus,  if  a  sensation 
changes  from  one  quality  to  another,  the  two  quali- 
ties are  critical  points,  and  in  so  far  as  the  change  is 
perceived  or  thought  of  under  the  dominance  of  its 
relations  to  these — or  their  relations  to  it — it  is  not 
mere  passing  time. 


PERCEPTION  231 

Attend,  in  so  far  as  you  can,  to  the  "  time  stream  " ; 
try  to  watch  the  "ceaseless  avalanche  of  time"  itself 
instead  of  attending  rather  to  the  events  caught  in 
its  rush,  as  you  normally  do,  and  you  will  find  that 
the  content  which  is  thus  emphasized  is  a  restless 
"going,  going,  going";  a  continual  motion  from 
nothing  in  particular  to  nothing  else  in  particular; 
just  continual  change.  This  change  may  be  in 
sensation,  or  in  imagery,  but  as  soon  as  it  is  defi- 
nitely located,  as  soon  as  the  whence  and  the  whither 
regain  their  normal  emphasis,  the  passing  time 
merges  into  concrete  change. 

In  transforming  the  world  of  immediate  experi- 
ence into  terms  of  substance  and  its  attributes,  we 
say  that  change  requires  Time  in  which  it  may 
occur;  we  postulate  time  as  a  sort  of  rack  into 
which  events  are  packed.  Such  Time,  if  it  exists, 
is  not  the  object  of  our  direct  perception,  and  al- 
though we  may  conceive  of  it  we  cannot  imagine 
it.  You  may  image  time,  but  it  is  always  as  it  is 
perceived,  a  concrete  succession  of  changes;  or 
rather  it  is  something  which  readily  becomes  such 
a  series  under  inspection.1 

1  Time,  with  a  capital  T,  is  a  metaphysical  construct  quite 
comparable  to  Space  with  a  capital  S.  This  is  sometimes 
called  '  physical '  time,  but  would  better  be  designated  '  logical ' 
or  '  mathematical '  time. 


232  A    SYSTEM   OF   PSYCHOLOGY 

A  succession  of  changes  presupposes  seriality, 
i.  e.,  intennediacy.  The  change  would  be  chaos  if 
m2  were  not  perceived  or  imaged  as  between  mi 
and  m:.  In  other  words,  we  intuit  in  the  change  a 
specific  relation  which  we  may  designate  as  tem- 
poral betweenness,  or  intermediacy.  This  inter- 
mediacy,  although  it  is  not  in  the  passing  time  as 
perceived,  is  an  element  in  all  other  time-content. 

Rate  of  change  is  measured  by  the  comparison  of 
two  series  in  content.  If  you  notice  a  certain  rate 
of  change  in  auditory  sensation,  you  are  comparing 
it  with  the  rate  of  change  of  such  other  sensory  or 
imaginative  content  as  is  implicitly  assumed  as  a 
standard.  The  perception  of  rate  passes  so  readily 
into  the  perception  of  extent  that  we  must  at  once 
consider  that  factor. 

(2)  Temporal  extent  is  the  amount  of  change  be- 
tween determining  points.  If  you  note  in  direct 
perception  how  long  a  sensation  lasts,  you  are  not- 
ing the  beginning  of  the  sensation  and  its  end, 
which  are  two  points  of  transition  in  the  field  of 
consciousness,  between  which,  if  we  were  restricted 
to  the  one  sensation,  and  it  were  uniform — if  it  did 
not  vary  in  any  character  from  beginning  to  end — 
there  would  be  no  perceived  time  at  all.  But  we 
arc  not  restricted  to  this  sensation,  and  we  perceive 


PERCEPTION  233 

changes  occurring  in  other  sensations — increase  or 
decrease  in  intensity,  and  so  on — which  in  their  re- 
lations to  the  determining  points  of  the  first  sen- 
sation constitute  the  perceived  time  between  those 
points.1 

The  duration  or  temporal  extent  may  be  made 
up  of  the  total  changes  in  the  content;  usually, 
however,  a  certain  part  of  the  content  is  selected, 
and  change  in  other  parts  is  not  included  in  the 
total.  The  selected  contents  are  normally  the  pe- 
riodic or  rhythmic  muscular  activities:  breathing, 
the  heart-beat,  or  periodic  movements  of  the  limbs, 
as  in  walking;  or  even  purposely  produced  pe- 
riodic contractions  of  other  muscles,  as  tapping  of 
the  finger  or  slight  movement  in  the  throat. 

For  practical  purposes  we  find  it  convenient  to 
use  as  standard  extents  of  time  the  cycles  of  change 
of  certain  cosmic  phenomena — the  periodic  pas- 
sage of  the  sun  across  the  meridian;  the  stellar  posi- 

1  The  character  of  sensation  which  we  have  called  duration, 
or  protensity,  is  not  to  be  confused  with  duration  in  the  sense 
of  temporal  extent.  The  sensation  would  be  perceived  even 
if  it  were  not  perceived  as  having  temporal  extent;  and  two 
sensations  having  different  physical  durations  would  be  per- 
ceived as  differing  in  protensity  even  although  no  time  were 
perceived  as  included  in  either. 

Protensity  is  the  character  of  sensation  by  virtue  of  which 
it  can  have  perceived  duration,  independently  of  any  changes 
it  may  itself  undergo.  Duration  proper  is  the  protensity 
fdled  out  by  change  in  other  sensation. 


234  A    SYSTEM  OF   PSYCHOLOGY 

tions;  and  so  on.  Ordinarily,  we  employ  as  unit 
the  day,  that  is,  the  interval  between  successive 
noons.  Primitive  man  subdivided  the  day  by  the 
positions  of  the  sun,  corrected,  doubtless,  by  the  pe- 
riodic need  and  satiety  of  sleep.  A  little  progress  in 
astronomical  observation  showed  the  variation  in 
solar  days  as  compared  with  the  sidereal,  and  the 
desire  for  harmonious  subdivisions  resulted  in  the 
partition  of  the  day  on  a  spatial  basis,  fifteen  de- 
grees of  longitude  being  the  measure  of  an  hour, 
fifteen  minutes  of  longitude,  one  minute  of  time, 
and  so  on.  These  astronomical  divisions  of  time 
are  by  no  means  equal  for  perception;  one  minute 
may  be  perceived  as  ten  times  as  long  as  the  next. 
The  symbolical  estimation  of  time  is  not  restricted 
to  the  means  of  astronomical  observations,  pendu- 
lums, and  such  physical  devices.  Very  often  we 
measure  intervals  by  the  number  of  recurrences  of 
physiological  phenomena;  as  heart-beats,  breaths, 
etc.;  without  regard  to  the  actually  perceived  time- 
content.  Before  this  trait  was  noticed  certain 
phenomena  of  time-estimation  were  quite  inexpli- 
cable; the  fact  that  intervals  corresponding  to  some 
multiple  of  the  respiration-period  were  more  accu- 
rately estimated  than  intervals  falling  between  these 
in  length  was  discovered  some  decades  ago,  and, 


PERCEPTION  235 

not  being  referred  to  the  respiration  at  the  time 
gave  rise  to  much  tenuous  speculation.  In  other 
cases  the  breathing  rhythm  seems  to  be  of  less  in- 
fluence and  the  heart-rate  to  dominate  the  estima- 
tions. 

In  the  direct  estimation  of  time,  any  variation  in 
the  processes  by  which  we  estimate,  or  any  change 
in  the  attention  to  them,  affects  the  estimation. 
The  apparent  duration  of  a  visual  phenomenon 
occupying  three  physical  seconds  will  not  differ 
greatly,  general  conditions  being  the  same,  from 
the  apparent  duration  of  an  auditory  phenomenon 
of  the  same  physical  measure.  In  neither  case  is 
the  time-content  the  change  in  the  auditory  or  vis- 
ual content,  but  in  some  content — muscular,  and 
perhaps  ideational — which  is  the  same  in  both 
cases;  the  beginning  and  the  end  of  the  estimated 
phenomenon  simply  mark  off  a  certain  amount  of 
this  change.  The  change  in  the  estimated  phe- 
nomenon is  perceived  simply  as  change,  the  rapid- 
ity thereof  being  determined  by  the  amount  of 
change  in  the  other  series — in  the  time — to  which 
it  corresponds. 

The  apparent  length  of  intervals  marked  off  by 
tactual  stimulations  varies  exceedingly  from  the 
apparent  length  of  intervals  marked  off  by  visual 


236  A   SYSTEM  OF   PSYCHOLOGY 

or  auditory  stimulation,  especially  in  being  more 
irregular.  This  peculiarity  of  tactually  limited  in- 
tervals is  probably  due  to  the  fact  that  attention  to 
tactual  stimulation  emphasizes  also  certain  muscu- 
lar sensations  from  the  member  tactually  stimulated, 
and  this  sensation  merges  in  an  irregular  way  with 
the  more  rhythmic  muscular  sensation  constituting 
the  basis  of  the  time-content. 

The  passing  of  time  seems  sometimes  slow,  some- 
times fast.  This  feature  arises  from  the  fact  that 
we  are  comparing  two  series  of  changes  whose  rel- 
ative rates  are  variable.  The  measure  of  the  time 
is  the  series  of  changes  we  may  call  St.  The  con- 
tent which  is  timed  by  that  measure,  the  mass  of 
sensation  from  the  world  about  us,  itself  in  constant 
change,  we  may  call  Sc.  Now,  while  the  rate  of 
change  of  <$/  is  reasonably  uniform — as  compared 
with  physical  standards — the  rate  of  change  of  Sc 
is  highly  irregular.1  If  Sc  is  changing  rapidly,  as 
when  a  great  many  interesting  events  are  happen- 
ing around  you,  time  is  perceived  as  flying.  If,  on 
the  other  hand,  Sc  goes  slowly,  as  on  days  of 
deathly  dulness,  time  is  perceived  as  dragging.  If 
all  the  changes  in  content  not  included  in  the  time 

1  Perhaps  we  should  say  merely  that  St  is  less  irregular  than 
Sc. 


PERCEPTION  237 

series  should  become  insignificant,  the  experience 
would  approximate  to  the  perception  of  eternity; 
those  who  have  been  the  subject  of  this  in  the  de- 
lirium of  fever  doubtless  remember  the  horror  of  it. 
In  retrospect,  the  time  that  dragged  may  seem 
brief,  as  compared  with  an  equal  physical  length  of 
the  time  that  flew.     This  seeming  inversion  of  the 
duration    relation   is   due   to   a   peculiarity   of  our 
estimation  of  time  intervals  whose  filling  has  once 
passed  from  consciousness.     When  you  reproduce 
a  series  of  past  events,  you  time  them  by  the  present 
muscular  series,  just  as  if  they  constituted  fresh 
content;  for  you  could  not,  if  you  would,  reproduce 
the  past  series  of  sensations  forming  the  time  basis. 
The  richer  series,  now  taking  longer  to  run  over  in 
memory  than  does  the  poorer  series,  marks  off  more 
change  in  the  time  series,  that  is,  it  seems  longer. 
On  the  other  hand,  the  events  of  the  past  interval 
may  not  appear  prominently;    you  may  remember 
that  they  excited,  interested,  bored,  or  otherwise 
emotionally  affected  you,  and  this  memory  may  serve 
as  the  symbol  of  the  time  length;    the  tedious  ex- 
perience may  be  thought  of  now  as  tedious  because 
the  memory  of  the  content  recalls  the  affective  or 
emotional  experience  connected  with  the  slow  pas- 
sage of  the  time. 


238  A    SYSTEM   OF   PSYCHOLOGY 

(3)  The  relations  of  past  to  present  and  to  future 
are  so  invariable  and  all  pervading  that  they  almost 
defy  analysis.  Practically  all  we  can  do  here  is 
to  point  them  out;  but  that  does  not  signify  that 
the  relations  are  simple. 

The  present  corresponds  to  the  "here"  of  space 
— the  origin  in  a  system  of  co-ordinates — and  past 
and  present  correspond  to  "elsewhere."  If  we  so 
desire,  we  can  carry  the  analogy  still  farther  in  con- 
nection with  the  factors  reality  and  unreality.  We 
may  imagine  either  past  or  future  as  real  (memory 
and  expectation),  or  as  unreal.  I  may,  for  ex- 
ample, imagine  myself  as  having  made  a  successful 
balloon  ascension  yesterday,  or  as  the  proprietor 
of  a  restaurant  to-morrow.  We  might  therefore 
liken  the  past  and  the  future  to  the  positive  and 
negative  directions  of  a  line,  and  the  fictitious  past 
and  future  to  the  ±i/~=1l.  But  the  analogy  breaks 
down,  for  the  "reality"  and  "unreality"  are  not 
time  factors,  and  we  can  imagine  content  as  present 
and  unreal,  as  well  as  present  and  real. 

"Reality"  may  be  taken  in  another  way,  to  sig- 
nify the  intuited  as  against  the  imagined.  This, 
again,  is  not  a  time  factor,  since  content  may  be 
cither  intuited  or  imagined  as  present.  It  is  only 
in  a  metaphysical  way  that  I  can  identify  the  present 


PERCEPTION  239 

with  reality,  and  past  and  future  with  unreality; 
for  this  identification  is  not  a  matter  of  immediate 
experience  at  all,  but  a  symbolic  way  of  stating  the 
time  relations.  In  so  far  as  my  immediate  experi- 
ence is  concerned,  both  past  and  future  actually 
exist.1 

The  temporal  factors  of  pastness  and  futurity 
have  essentially  connected  with  them  the  factors  of 
familiarity  and  novelty.  What  is  apprehended  as 
past  is  also  recognized,  that  is,  it  has  the  element  of 
familiarity;  but  we  cannot  say  that  pastness  and 
familiarity  are  one  and  the  same  thing.  Familiar- 
ity, it  is  clear,  may  attach  to  a  content  which  has 
novelty;  something  may  be  both  future  and  famil- 
iar.    It  is  quite  possible  that  these  factors  are  ulti- 

1  There  are  many  interesting  problems  in  the  metaphysical 
view  of  time.  If  the  past  does  not  exist,  any  account  of  it  is 
pure  fiction,  and  history  and  mythology  are  alike  only  at- 
tempts to  systematize  a  present  content,  true  in  so  far  as  they 
succeed;  historical  truth  depending  therefore  merely  on  the 
extent  and  quality  of  our  present  information.  To  say  that 
the  past  docs  not  exist,  but  did  exist  is  a  mere  quibble,  just  as 
it  is  to  say  that  to-morrow  will  be  Monday.  If  the  past  is, 
then  the  events  of  the  past  were;  if  to-morrow  is,  then  the 
events  thereto  pertaining  will  be.  To  say  that  to-morrow  will 
be,  or  that  the  past  was,  is  either  a  misstatement  or  a  meta- 
phor. 

Whatever  the  "reality"  factor  of  content  may  be,  analysis 
so  far  has  simply  indicated  it.  It  is  doubtless  a  relation  or 
group  of  relations — a  "feeling  of  realty,"  the  current  empirical 
philosophy  would  call  it — and  there  we  are  obliged  to  leave 
it  for  the  present. 


240  A   SYSTEM   OF   PSYCHOLOGY 

mate  elements,  and  we  may  accept  them  as  such 
provisionally. 

The  present  moment  of  perceived  time  may  be 
said  to  be  a  mere  position  in  which  all  content  has 
its  origin,  and  from  which  it  ceaselessly  flows.  This 
present  moment,  in  other  words,  does  not  include 
any  duration.  In  this  respect  it  is  like  the  present 
moment  of  logical  ("physical ")  time,  which  must  be 
represented  as  a  mere  point  on  a  line.  The  actual 
present,  however,  cannot  be  represented  by  the 
logical  present;  that  is  to  say,  that  when  the  actual 
present  moment  is  schematized  in  such  a  way  as  to 
show  the  various  features  of  content  and  of  proc- 
esses connected  with  it,  in  logical  time  relations, 
this  present  is  represented  not  by  a  point,  but  by  an 
appreciable  extent  of  "physical"  time. 

Another  way  of  describing  the  relation  between 
the  actual  present  and  the  logical  present  is  to  say 
that  the  content  may  include  factors  which  ap- 
pear simultaneous,  but  whose  physical  causes  (and 
probably  whose  physiological  processes)  are  sepa- 
rated by  some  interval  in  the  physical  series.  For 
example:  a  hand  revolving  over  a  dial  may  pass 
the  zero  mark  a  fraction  of  a  second  before  or  after 
a  bell  stroke  occurs,  and  yet  the  two  occurrences 
may  seem  simultaneous.     The  perception   of  the 


PERCEPTION  241 

pointer  at  a  definite  place  on  the  dial  necessitates 
an  eye  movement,  which,  in  some  way  not  entirely 
understood  at  present,  allows  an  "instantaneous 
photograph"  on  the  retina  of  the  pointer  at  the  given 
place;  without  this  eye-movement  the  image  blurs. 
When  the  click  appears  immediately  before  or  after 
the  eye  movement  no  time  is  perceived  as  inter- 
vening, that  is,  the  visual  impression  and  the  audi- 
tory impression  are  judged  to  be  simultaneous. 


CHAPTER  XIV 

AFFECTIVE  CONTENT  OR  FEELING 
i.  Affection  and  Cognition 

Perception  and  imagination  are  classed  as  cog- 
nition, and  sensation  and  relations,  therefore,  as  cog- 
nitive elements.  These  factors  do  not  exhaust  the 
sum  of  content,  or  at  least  there  are  sorts  of  con- 
tent which  have  not  been  demonstrated  as  reduc- 
ible to  sensation  and  relation. 

When  I  experience  an  object,  I  may  experience 
it  qualified  by  pleasantness  or  the  opposite.  A  cer- 
tain amount  of  what  for  want  of  a  better  term  we 
may  call  interest  may  also  attach  to  the  object.  If 
I  imagine  a  content  it  may  be  tinged  with  desire  or 
repugnance.  These  factors — pleasure,  pain,  de- 
sire, repugnance,  and  interest — constitute  the  affec- 
tive tone  of  the  content  in  so  far  as  they  are  present. 
They  are  sometimes  looked  upon  not  as  factors  in 
the  content,  but,  (1)  as  ways  of  experiencing  it,  or 
(2)  as  attitudes  toward  it,  or  (3)  modes  in  which  the 
ego  is  affected  in  experiencing  it.  These  three  ex- 
pressions, which  are  practically  equivalent,  mean 

242 


AFFECTIVE    CONTENT   OR    FEELING  243 

nothing  more  than  that  the  content  of  experience 
is  not  completely  accounted  for  in  analysis  in  terms 
of  cognitive  factors  only;  that  the  non-cognitive 
or  affective  factors  are  as  truly  sui  generis  as  are 
the  cognitive  factors. 

Affective  content  includes  not  only  the  elements 
(or  quasi-elements)  just  mentioned,  but  also  the 
more  complex  factors  called  emotions  and  emotional 
tone.  For  example,  the  content  may  be  joyful, 
pathetic,  humorous,  or  revolting. 

Pleasure,  pain,  interest,  desire,  and  repugnance, 
may  be  designated  as  feelings,  or,  abstractly,  as 
feeling.  Pleasure  and  pain  are  designated  as 
hedonic  tone  or  algo-hedonic  tone;  the  experience  of 
pleasure  and  pain,  considered  generally,  is  hedono- 
algesis.1  Desire  and  aversion  are  designated  ad- 
jectively  as  conative  or  appetitive,  and  the  experience 
of  them  as  conation  or  appetition. 

1  The  term  "feeling  tone"  is  commonly  given  to  pleasure- 
pain  alone:  frequently  the  two  qualities  are  designated  as 
pleasantness  and  unpleasantness.  Some  psychologists  apply 
the  term  "feeling  tone"  also  to  certain  obviously  sensory 
elements  or  factors,  especially  strain  and  relaxation. 

"  Feeling"  has  been  much  used  in  the  past  in  the  sense  of 
emotion,  but  is  not  so  usecF  at  present  in  strict  discourse. 

Often,  however,  the  term  is  extended  to  cover  what  we 
have  designated  as  relational  content;  thus,  a  "feeling  of 
similarity"  is  not  an  uncommon  expression.  In  loose  speak- 
ing, "feeling"  is  used  to  designate  any  sort  of  content  what- 
ever. 


244  A   SYSTEM   OF   PSYCHOLOGY 

The  most  conspicuous  feature  of  feeling  and 
emotion  is  the  pairing  off  of  the  different  qualities 
and  qualitative  complexes  in  antithetical  fashion. 
The  two  conative  qualities  are  mutually  opposed  to 
each  other,  as  are  also  the  algo-hedonic  qualities, 
and  for  almost  every  emotion  there  is  an  opposite. 
This  raises  the  suspicion  that  all  the  emotions  are 
based  on  the  feelings,  and  that  very  probably  there 
are  more  feelings  than  the  ones  we  have  named. 

2.  Pleasure  and  Pain 

Hedonic  tone  attaches  not  only  to  sensational 
experiences  but  also  to  content  of  all  kinds.  An 
idea  is  pleasant  or  unpleasant;  the  memory  of  your 
misfortune  yesterday  involves  painful  elements,  the 
idea  of  the  good  time  to-morrow  brings  pleasure 
with  it.  The  recognition  of  relations,  whether  in 
idea  or  immediate  perception,  rouses  hedonic  or 
algetic  factors,  and  sometimes  vividly;  even  the 
solution  of  a  problem  in  Euclid  brings  pleasure. 
Emotional  states  can  be  classified  on  the  basis  of 
their  hedonic  tone. 

In  some  respects  hedonic  tone  resembles  sensa- 
tion. It  has  the  characters  of  quality,  intensity,  and 
duration.  Other  forms  of  content  (relations,  pos- 
sibly images,)  can  hardly  be  said  to  possess  inten- 


AFFECTIVE    CONTENT    OR   FEELING 


245 


sity.  Affective  elements  have  no  specific  physical 
stimuli:  in  this  respect  they  resemble  visceral  sensa- 
tions. But  on  the  other  hand,  the  feelings  cannot 
be  identified  with  any  peripheral  nervous  mechan- 
ism or  process;  in  which  they  are  analogous  to  rela- 
tions. 

The  quality  and  intensity  of  hedonic  tone  ac- 
companying sensations  are  determined  by  the  sen- 


UNPl 


Fig.  12. 

The  curves  in  fig.  12  represent  schematically  the  relation  between 
feeling  and  sensation  intensity.  The  abscissa  represents  the  intensity 
of  the  sensation,  and  the  plus  and  minus  ordinates  represent  the  corre- 
sponding degrees  of  pleasantness  and  unpleasantness  respectively. 


sations  in  fairly  simple  ways.  The  intensity,  dura- 
tion, and  the  number  of  repetitions  of  the  sensation 
seem  to  be  the  important  factors.  If  the  sensation 
is  of  brief  duration,  it  is  usually  pleasant  at  low 
intensities,  the  degree  of  pleasure  depending  on  the 
sensation-quality,  and  on  the  individual  and  his 
condition.     To  most  of  us,  a  faint  smell  of  lilac  is 


246  A    SYSTEM   OF   PSYCHOLOGY 

agreeable,  but  as  the  intensity  of  the  odor  increases 
the  pleasure  decreases,  changing  for  some  persons 
to  unpleasantness  with  high  intensity  of  the  sensa- 
tion. (See  Curve  II  of  Fig.  12.)  For  other  per- 
sons the  odor  may  remain  pleasant  at  relatively  high 
intensities.  (Curve  I.)  For  the  most  part,  sen- 
sations are  slightly  pleasant  when  sufficiently  faint, 
(Curve  III),  although  some  are  indeed  merely 
neutral,  and  some  are  unpleasant  for  some  persons 
if  above  the  threshold  at  all.     (Curve  IV.) 

The  duration  of  the  sensation  exercises  an  influ- 
ence on  hedonic  tone;  or,  rather,  the  tone  varies  ac- 
cording to  the  duration  of  the  sensation.  A  flash 
of  color,  a  brief  skin-tickle,  a  whiff  of  musk,  may 
be  agreeable,  although  a  longer  continuation  makes 
the  sensation  intolerable.  In  the  cases  of  some  sen- 
sations, the  feeling  may  not  be  changed  to  the  oppo- 
site, but  simply  become  less  pleasant  or  more  un- 
pleasant; but  the  effect  of  a  longer  duration  of  the 
sensation  is  always  to  send  the  tone  in  the  unpleasant 
direction.  At  the  same  time,  it  must  be  remem- 
bered, the  continuance  of  a  stimulation  produces 
progressively  less  response  from  the  sense-organ, 
and  hence  less  intensity  of  sensation. 

Repetition  may  make  a  sensation  which  is  orig- 
inally unpleasant  less  so,  or  even  pleasant.     Bitter 


AFFECTIVE    CONTENT   OR   FEELING  247 

becomes  a  pleasant  taste,  and  discord  a  pleasant 
sound,  with  habituation  thereto.  Possibly  all  food 
flavors  are  unpleasant  to  the  child  experiencing 
them  for  the  first  time;  the  instinct  to  eat  and  the 
desire  to  do  what  others  do  impel  him  to  continue 
to  ingest  the  food  and  drink  offered  to  him,  and  he 
quickly  learns  to  like  them.  Where  a  sensation  be- 
comes more  unpleasant  with  repetition,  the  organ 
has  undergone  a  change — pathological,  perhaps — 
such  that  the  stimulus  really  produces  a  more  in- 
tense sensation,  as  in  the  case  of  a  tooth  which  the 
dentist  has  been  torturing  intermittently;  or  ideal 
factors  have  entered,  with  their  effects  on  feeling, 
as  when  one  revolts  from  a  formerly  toothsome 
dish  after  seeing  the  details  of  its  preparation. 

In  the  realm  of  ideas  and  relations  the  conditions 
governing  pleasure  and  pain  are  highly  complicated. 
That  we  can  remember  or  imagine  affective  ele- 
ments is  denied  by  some  psychologists.  Perhaps 
individuals  differ  in  their  power  of  imagining  such 
contents.  On  the  other  hand,  the  idea  or  image  of 
past  or  future  experience  may  arouse  actual  pleasure 
or  pain  at  the  moment  of  the  experience  of  the 
idea,  and  so  the  belief  in  reproduced  hedonic  tone 
may  be  due  to  the  mistaking  of  the  tone  of  the 
image  for  the  image  of  the  tone.     The  idea  of  past 


248  A    SYSTEM   OF    PSYCHOLOGY 

events  is  not  always  pleasant  if  the  past  content  was 
pleasant,  nor  unpleasant  if  the  past  content  was 
unpleasant.  The  determining  causes  of  hedono- 
algetic  quality  seem  to  lie  deep,  and  to  operate  in 
sense  perception  as  well  as  in  ideation;  the  quasi- 
principles  above  laid  clown  in  regard  to  sensation 
being,  perhaps,  specific  results  of  these  general 
causes. 

In  the  first  place,  the  normal  physiological  activi- 
ties, those  which  go  on  as  they  should  for  the  wel- 
fare of  the  individual  and  the  perpetuation  of  the 
species,  give  pleasure;  any  interference  with  the 
usual  course,  or  anything  detrimental  to  the  organ- 
ism, gives  pain.1 

In  the  second  place,  whatever  simulates  some 
condition  which  is  organically  advantageous,  gives 
pleasure.  Drugs  which  produce  effects  on  the  ner- 
vous system  temporarily  like  the  effects  of  rest  or 


1  This  connection  of  algo-hedonic  tone  with  the  normal  may 
be  supposed  to  be  the  result  of  natural  selection.  Animals 
which  failed  to  get  pain  from  mutilation,  exhaustion,  or  hun- 
ger, and  pleasure  from  food  and  the  society  of  the  opposite 
sex,  would  have  less  chance  for  individual  and  racial  survival 
than  those  which  were  "normal"  in  that  regard.  We  should 
expect  to  find  certain  capacities  for  pleasure,  e.  g.,  of  intoxica- 
tion, which  are  in  themselves  harmful,  that  have  not  been 
eliminated  because  of  their  connection  with  other  and  bene- 
ficial activities,  or  because  natural  selection  has  had  no  chance 
at  them. 


AFFECTIVE    CONTENT   OR   FEELING         249 

normal  activity  produce  also  the  pleasurable  ac- 
companiments of  these  conditions. 

In  the  third  place,  the  carrying  out  or  comple- 
tion of  any  activity;  the  accomplishment  of  any 
purpose;  or  the  contemplation  of  a  purpose  ac- 
complished, give  pleasure.  The  hindering  or  ob- 
structing of  activity;  the  failure  to  carry  out  a  pur- 
pose; the  contemplation  of  a  plan  obstructed  or 
an  accomplishment  obliterated;  any  of  these  give 
pain.  Solving  a  problem,  carrying  out  schemes  of 
politics  or  business,  playing  a  game  successfully, 
contemplating  your  rise  from  barefoot  boy  to 
banker — these  are  instances  of  the  one  sort.  Get- 
ting "stuck"  in  a  problem,  failing  to  get  command 
of  a  game,  recalling  your  recent  wealth  or  influ- 
ence, are  instances  of  the  other. 

The  general  rule,  in  short,  is  that  the  normal  and 
successful  performance  of  functions,  physiological 
or  mental,  is  accompanied  by  pleasure,  and  the 
fact  that  certain  exceptions  occur  is  evidence  merely 
that  the  physio-psychological  mechanism  is  not  per- 
fectly adapted  for  all  contingencies. 

As  soon  as  we  recognize  pleasure  and  pain  as 
primarily  the  concomitants  of  the  organic  welfare 
of  the  individual,  we  are  led  to  suspect  that  they 
are  forms  of  visceral  sensation.     We  mi"'ht  reason- 


250  A    SYSTEM   OF   PSYCHOLOGY 

ably  suppose  that  the  well-being  of  the  vital  organs, 
and  the  proper  discharge  of  their  functions,  cause 
the  stimulation  of  appropriate  nerve  endings,  and 
as  a  result,  somewhere  in  brain  or  in  spinal  cord, 
takes  place  the  neural  process  specifically  corre- 
sponding to  pleasure.  So  too,  the  vital  organs  in 
unfavorable  circumstances  might  arouse  sensations 
of  pain.  Nervous  excitations  through  the  organs 
of  "  external "  sense,  or  the  neural  correlate  of  idea- 
tional activity,  being  intimately  connected  with  the 
condition  of  the  organism,  have  possibly  acquired 
either  the  power  to  excite  the  visceral  organs  by  re- 
flex nervous  discharges,  or  else  the  power  to  excite 
directly  the  neural  centre  of  hedono-algetic  feeling. 
This  sensational  theory  of  pleasure  and  pain  is 
to  be  regarded  merely  as  a  live  hypothesis.  It  is 
not  at  present  any  more  probable  than  the  oppo- 
site hypothesis;  viz.,  that  pleasure  and  pain  are 
content  of  a  kind  different  from  sensation. 

3.  Conation  and  Interest 

Desire  and  repugnance  are  antithetical,  as  are 

pleasure  and  pain,  and  are  usually  so  connected 

with  the  lat'ter  functionally  that  what  is  pleasant  is 

desired,  and  what  is  unpleasant  is  repugned.1 

1  We  use  here  the  verb  "repugn  "  as  the  exact  opposite  of  the 
verb  "desire".     This  usage  is  rare  in  English  literature,  but 


AFFECTIVE    CONTENT   OR   FEELING  251 

Conative  factors  attach  only  to  imaged,  ideated, 
and  conceived  content.  If  an  object  is  present  to 
sense — intuited — it  is  pleasing  or  displeasing,  but 
cannot  be  desired  or  repugnant.  When  an  object 
is  perceived,  some  further  content  connected  with 
it  may  be  conatively  colored.  Thus,  when  fruit  is 
before  my  gaze,  I  cannot  desire  the  sight  of  it,  for 
that  I  already  have;  but  I  may  desire  the  taste,  or 
a  continuance  of  the  sight,  or  the  complex  relations 
known  as  ownership.  So  the  nasty  medicine  forced 
on  the  child  is  not  repugnant  as  he  experiences  it, 
but  the  taste  and  effects  imagined  as  a  future  pos- 
sibility are  decidedly  repugnant. 

Interest  is  verbally  the  opposite  of  apathy,  but 
the  two  factors  are  not  antithetical,  as  are  desire 
and  repugnance.  Apathy  is  really  the  zero-point 
of  interest,  corresponding  to  the  neither-pleasant- 
nor-painful;  the  neither-desired-nor-repugnant. 
There  is  only  one  quality  of  interest.  A  high  de- 
gree of  interest  may  coincide  with  either  the  pleas- 
ant or  the  painful,  the  desired  or  the  repugnant. 

it  is  necessary  to  make  this  addition  to  psychological  termin- 
ology because  we  have  no  other  word  which  can  serve  as  a 
precise  term  for  the  opposite  of  "desire."  "Aversion"  is  fre- 
quently used  for  the  noun,  but  is  not  unambiguous,  and  has  no 
verb  form.  We  might  even  venture  a  step  beyond  precedent 
and  use  the  noun  "repugn"  as  the  opposite  to  the  noun  "de- 
sire." 


252  A    SYSTEM   OF   PSYCHOLOGY 

The  glorious  sunset;  the  vile  chemical  laboratory 
smell;  the  recollected  images  of  yesterday's  good 
fortune;  the  idea  of  to-morrow's  catastrophe;  all 
may  be  permeated  by  intense  interest. 

Interest  attaching  to  one  feature  of  a  complex 
content  spreads  over  the  other  factors  of  the  con- 
tent. The  firmer  the  association  between  the  in- 
trinsically interesting  factor  and  the  other  factors, 
the  more  these  share  in  its  interest.  Pedagogues 
universally  recognize  this  fact,  and,  therefore,  in  pre- 
senting any  subject  to  children,  they  inject  anec- 
dotes, bring  out  details  which  are  not  essential  to 
the  subject-matter,  but  which  are  interesting  to  the 
child,1  and  in  every  other  way  possible  mingle  with 
the  dry  material  interesting  stuff  which  can  be  as- 

1  It  is  customary  to  say  "appeal  to  the  child's  interest,"  in- 
stead of  "possess  interest  for  the  child."  This  form  of  ex- 
pression indicates  the  survival  of  the  view  of  content  of  vari- 
ous sorts  as  products  of  the  "faculties"  of  the  individual. 
Under  the  "faculty"  theory  the  various  terms  designating 
different  divisions  of  the  field  were  applied  indiscriminately  to 
the  content  and  to  the  hypothetical  "  faculty"  producing  the 
content.  This  "  faculty  psychology"  is  by  no  means  dead  at 
present,  and  has  the  greatest  vitality  in  the  realm  of  the  feel- 
ings. The  student  must  be  careful  not  to  allow  the  common 
ways  of  speaking  of  psychological  facts  to  draw  him  into  a 
false  understanding  of  them.  You  may  say  "I  admire  St. 
Gaudens'  statues"  and  "I  became  interested  in  polar  explora- 
tion," but  don't  forget  that  admiration  and  interest,  to  what- 
ever activities  they  may  lead,  are  factors  in  the  content  of 
your  consciousness,  and  not  anything  supplied  by  your  con- 
sciousness  or  your  ego. 


AFFECTIVE   CONTENT   OR   FEELING  2o3 

sociated  with  it.  Contemporaneous  events;  de- 
tails concerning  the  person,  country,  or  organiza- 
tion under  consideration,  and  especially  causes 
and  effects,  form  associative  nexus  over  which  the 
interest  readily  travels.  But  even  such  artificial 
associations  as  may  be  formed  between  f  and  the 
red  apples  used  to  illustrate  the  problem,  may 
carry  interest  from  the  fruit  to  the  arithmetic, 
for  the  good  of  the  child  and  the  success  of  the 
teacher. 

Desire  and  repugnance  spread,  but  not  simply 
along  the  lines  of  association.  In  certain  cases  the 
invariable  associates  of  desired  or  repugnant  things 
become  invested  with  the  given  feeling,  sometimes 
to  the  exclusion  of  that  which  it  originally  attached; 
but  these  cases — fetichism,  so  called — are  excep- 
tional. In  general,  the  organic  whole  which  is 
ideated — for  example,  a  trip  to  Europe — is  desired 
(or  the  reverse)  in  so  far  as  one  or  more  important 
factors  in  the  idea  have  the  feeling,  but  the  cona- 
tive  feeling  does  not  tend  to  flow  over  and  color  the 
other  cognitive  factors,  or  at  least  not  to  the  same 
extent  as  does  interest.  However  ardently  you 
desire  the  European  trip,  the  sea  voyage  essential 
thereto  may  remain  repugnant,  and  certain  details 
of   continental    travel    remain    conatively    neutral. 


254  A    SYSTEM   OF   PSYCHOLOGY 

But  vour  interest  in  the  means  and  conditions  of 
travel  swells  almost  in  proportion  to  your  interest 
in  foreign  lands. 

In  the  particular  instance  cited,  the  abhorred 
factor — the  ocean  trip — becomes  desired,  in  spite 
of  its  unpleasantness,  as  soon  as  you  begin  to  make 
definite  plans  for  beginning  your  vacation.  You 
contemplate  the  voyage  as  a  necessary  link  in  the 
chain  of  causation  which  will  bring  the  intrinsic- 
ally desired  details  of  the  stay  on  the  other  side. 
Conative  feeling,  in  other  words,  spreads  along  the 
line  of  causal  relation  in  the  regressive  direction.  If 
you  desire  anything,  you  will  desire  the  causes 
thereof,  unless  those  causes  are  so  tinctured  with 
repugnance  that  the  desire  of  the  effects  cannot 
overcome  it.  There  are  persons  who  are  such 
"poor  sailors"  that  not  all  the  joys  of  the  other 
continents  can  overcome  their  aversion  to  the  un- 
easy ocean. 

Conative  feeling  never  spreads  progressively  along 
the  line  of  causation.  You  may  be  averse  to  the 
sea  voyage  because  of  the  repugnant  consequences; 
but  no  matter  how  much  you  desire  to  take  ship, 
the  consequent  mal  de  mer  will  never  become  in  the 
least  desired.  However  fierce  may  be  your  long- 
ing for  any  pleasurable  content,  it  will  not  add  one 


AFFECTIVE    CONTENT   OR   FEELING  255 

jot  to  your  desire  for  the  consequences,  nor  sub- 
tract one  tittle  from  your  repugn  for  them. 

The  desire  or  repugnance  attaching  to  a  cause — 
or  what  is  conceived  as  a  cause — does  have  an  in- 
fluence on  the  interest  attaching  to  the  effect.  If 
the  effect  has  the  opposite  conative  feeling,  it  is  de- 
creased in  interest,  sometimes  even  to  the  apathetic 
point.  The  dipsomaniac,  eager  for  the  pleasant 
excitement  of  intoxication,  does  not  desire  the  next 
day's  wretchedness;  but  that  result  he  refuses  to 
ideate — it  has  no  interest  for  him  while  his  desire  for 
intoxication  lasts,  and  interest,  as  we  shall  see, 
is  one  of  the  important  conditions  of  attention.  In 
this  curious  relation  of  interest  to  antagonistic  cona- 
tive feeling  is  doubtless  to  be  found  a  clew  to  the 
further  understanding  of  interest. 

4.  Emotion 

Emotion  includes  in  the  first  place  the  affective 
elements  just  mentioned,  and  perhaps  other  such 
elements.  In  the  second  place,  it  includes  among 
its  factors  bodily  sensation,  and  in  the  third  place 
intellectual  factors.  Sensory  imaginative  content 
is  included  in  many  instances. 

The  affective  elements  are  combined  in  an  organ- 
ized content  in  normal  consciousness  in  the  manner 


256  A    SYSTEM   OF   PSYCHOLOGY 

we  have  indicated  in  the  preceding  section;  either 
hedonic  tone,  or  either  conative  factor  may  appear 
with  any  degree  of  interest:  if  both  hedonic  tone 
and  conative  factors  are  present,  (as  in  ideation), 
repugnance  goes  with  pain  and  desire  with  pleasure. 
In  morbid  imagination  the  conditions  may  be  re- 
versed; pleasure  may  be  coupled  with  repugnance 
and  pain  with  desire. 

A  few  examples  of  affective  combination  in  emo- 
tion will  illustrate  the  possible  exclusions  of  one  or 
another  of  the  three  feeling  groups.  Grief  or  joy 
may  be  entirely  devoid  of  desire  and  aversion. 
Grief  may  lose  interest  until  it  sinks  approximately 
to  apathy.  Ennui  is  painful,  rather  apathetic,  and 
repugnant  in  so  far  as  its  continuance  is  ideated. 
On  the  other  hand,  the  idea  of  the  removal  of  its 
cause  is  pleasant  and  desired.  Hate  may  be  de- 
void of  hedonic  tone,  and  full  either  of  desire  or 
repugnance,  according  as  the  object  of  the  hate  is 
thought  of  as  suffering  or  prospering. 

Examples  of  morbid  emotion  are  found  in  cases  of 
asceticism  where  the  "pleasures  of  the  flesh"  are 
thought  of  with  aversion,  and  various  sorts  of  pain 
arc  desired.  The  ideal  of  the  monkish  life  is  to  rid 
the  ideas  of  things,  commonly  desired  or  repugnant, 
of  their  normal  pleasure  or  pain:   in  so  far  as  this 


AFFECTIVE    CONTENT   OR   FEELING  257 

ideal  is  realized  the  emotions  are  not  morbid;  they 
are  abnormal  only  in  the  sense  of  being  unusual. 
It  is  possible  that  in  some  diseased  mental  conditions 
(other  than  the  quasi-ascetic)  the  patient  may  desire 
what  is  thought  of  as  painful,  and  be  averse  to  what 
is  thought  of  as  pleasant. 

In  aesthetic  emotion  desire  and  repugnance  are  ex- 
cluded. My  present  emotion  with  regard  to  the 
Fifth  Symphony  of  Beethoven  is  not  aesthetic;  it  is 
a  commonplace  affair  in  which  the  desire  to  hear  the 
symphony  predominates:  the  emotion  while  listening 
to  the  symphony  is  aesthetic  if  no  desires  are  mingled 
in  it.  The  painting  of  a  mere  basket  of  fruit  can 
hardly  arouse  aesthetic  emotion,  because  the  desire 
to  taste  the  fruit  is  excited  if  the  painting  is  skilfully 
done  (there  are  exceptions,  however),  and  the  repre- 
sentation of  a  beautiful  woman  is  decidedly  un- 
aesthetic  if  it  arouses  sensuous  desire.  So,  too,  in  so 
far  as  anything  arouses  repugnance,  it  is  an  unaes- 
thetic  object.1 

The  ideals  of  art  are  not  satisfied  by  the  mere 
arousal  of  aesthetic  emotion.     Art  aims  to  carry  us  to 


1  The  ideal  religious  emotion  is  complementary  to  aesthetic 
emotion,  in  that  desire  and  repugn  are  included,  and  pleasure 
and  pain  excluded.  The  common  type  of  religious  emotion, 
or  what  passes  for  such,  is  generally  tinctured  heavily  with 
hedono-algetic  factors. 


258  A    SYSTEM   OF   PSYCHOLOGY 

the  point  where  the  sensuous  and  intellectual  con- 
tent is  minimized,  and  the  feeling  element  is  para- 
mount. This  aim  can  be  attained  measurably  by 
painting  and  sculpture,  but  more  adequately  by 
poetry  and  music.  In  poetry,  the  ideas  called  up 
by  the  words  are  necessarily  definite  and  in  so  far 
obtrusive,  but  the  skill  of  the  poet  is  exerted  to 
subordinate  this  machinery  to  the  results  achieved 
by  its  aid.  This  is  the  reason  why  description, 
narration,  or  philosophizing,  essentially  interfere 
with  the  poetic  effect,  although  they  may  produce 
a  pleasing  result;  and  the  poet  accordingly  employs 
them  only  in  so  far  as  the  ideas  they  arouse  are 
fragmentary  and  therefore  subordinate  to  their 
feeling. 

In  music,  we  are  less  trammelled  by  the  cognitive. 
The  mere  sounds  are  not  of  high  interest  in  the 
total  complex,  and  they  do  not  in  general  arouse 
definite  ideas.  There  are  exceptions,  in  what  is 
known  as  "  programme-music,"  in  which  certain  pas- 
sages are  supposed  to  suggest  the  singing  of  birds 
in  the  woods,  etc.,  and  although  some  musicians 
condemn  this  intrusion  of  ideas,  it  may  be  helpful 
in  some  cases.  The  mingling  of  music  with  sensu- 
ous and  intellectual  content  in  opera,  while  a  lower 
form  of  art  for  those  able  to  appreciate  pure  music, 


AFFECTIVE   CONTENT   OR   FEELING  25!) 

may  be  a  means  by  which  more  powerful  feeling 
is  roused  in  certain  persons  than  they  would  other- 
wise experience.  The  purity  of  the  feelings  is  one 
ideal,  and  the  strength  of  feeling  and  richness  of 
content  is  another,  between  which  the  choice  is  a 
matter  of  personal  response. 

5.  The  Coenaesthetic  Factor  in  Emotion 

The  discovery  that  emotion  contains  much  vague 
and  undiscriminated  bodily  sensation  was  made 
about  thirty  years  ago,  simultaneously,  by  James  of 
Harvard  and  Lange  of  Copenhagen.  Prior  to  that 
time  the  opinion  prevailed  that  the  bodily  factors  we 
experience  when  emotionally  moved  are  conse- 
quences of  the  emotion  proper — the  theory  of  Des- 
cartes. Spinoza  had  stated  the  doctrine  of  the 
bodily  factors  as  an  integral  part  of  the  emotion,  but 
in  a  crabbed  and  symbolic  way  which  produced  but 
slight  effect  on  psychology.  Lange  and  James 
went  so  far  as  to  claim  that  the  emotion  consists 
wholly  of  bodily  sensation — the  so-called  James- 
Lange  theory — and  although  we  are  not  inclined  to 
grant  this  claim  it  is  not  because  we  are  essentially 
at  variance  with  the  James-Lange  view,  but  because 
they  mean  by  emotion  only  what  is  left  over  after 
the  intellectual  and  ideo-cognitive  factors  are  ex- 


260  A    SYSTEM   OF   PSYCHOLOGY 

eluded,  and  possibly  after  the  exclusion  of  what  we 
have  designated  as  the  true  affective  factors,  while 
we  prefer  to  use  the  term  in  the  wider  sense  in 
which  the  public  understands  it.1 

The  trembling  of  the  limbs,  the  modified  beat 
of  the  heart,  the  peculiar  visceral  states,  and,  per- 
haps, the  results  of  certain  glandular  activities,  are 
certainly  a  large  factor  in  fear,  and  if  they  are  ab- 
stracted the  characteristic  emotion  is  dispelled. 
So  in  the  case  of  pathos;  the  emotion  derives  its 
specific  character  from  certain  sensations  connected 
with  swallowing  and  relaxation,  characteristic  of 
satisfaction,  and  with  the  retching  movements 
characteristic  of  disapproval  or  disgust;  for  the 
essential  thing  in  pathos  is  a  mingling  of  these  two 
emotional  complexes.  Other  illustrations  of  the 
cceniesthetic  factor  in  emotion  may  readily  be  found. 

The  mass  of  sensation  in  emotion  is  undiscrimi- 
nated and  vague.  When  you  pick  out  this  factor 
and  identify  it  with  the  respiration,  and  identify  that 
factor  with  the  leg  muscles,  and  the  other  factor  with 
the  intestinal  condition,  the  emotion  is  thereby  de- 
stroyed.    It  is  only  so  long  as  these  sensations  fuse 

1  For  a  statement  of  Professor  James's  theory,  and  the  multi- 
tude of  facts  which  support  it,  read  the  chapters  on  "  Instinct 
and  Emotion  "  (XXIV  and  XXV),  in  vol.  II,  of  his  Principles 
of  Psychology. 


AFFECTIVE    CONTENT    OR    FEELING  201 

into  an  undifferentiated  mass  that  they  area  "color" 
or  "background"  for  the  cognitive  content;  when 
discriminated  they  are  cognitive  content  themselves, 
losing  their  quasi-unique  character.  Moreover, 
the  visceral  sensations  are  always  vague,  and 
identification  of  them  is  difficult,  even  when  one 
makes  great  effort  to  analyze. 

It  is  possible  that  in  many  cases  the  actual  sensa- 
tions are  replaced  by  images  thereof;  so  that  a  man 
whose  heart  and  diaphragm  no  longer  respond  to 
the  stimulation  of  a  threatening  circumstance  still 
may  feel  fear  through  the  recall  of  the  appropriate 
sensations  in  imagination.  This  supposition  would 
be  contrary  to  the  seeming  fact  that  bodily  sensations 
are  in  general  not  imagined,  but,  nevertheless,  it  is 
not  yet  excluded. 

6.  The  Cognitive  Factor  in  Emotion 

An  emotion  is  always  built  up  on  some  cognitive 
content,  and  loses  its  distinctive  character  when  con- 
sidered apart  from  that  factor.  The  reference  of 
the  emotional  complex  to  the  "object"  of  the  emo- 
tion furnishes  the  basis  of  its  specific  organization. 
Emotional  content  not  attached  to  a  specific  cogni- 
tive content — which  has  not  a  specific  "object" — 
is  not  dignified  with  the  name  of  arc  emotion,  but 


262  A    SYSTEM   OF   PSYCHOLOGY 

is  called  an  emotional  mood.  Joy  and  sorrow,  di- 
vested of  the  definite  reference  to  the  object  or  event 
which  they  envelop,  become  mere  elation  or  depres- 
sion. Hate  which  is  not  the  hate  of  some  one  or 
thing  is  a  mere  savage  mood.  These  moods  are 
common,  and  may  be  produced  by  strictly  physio- 
logical causes;  melancholy,  the  mood  correspond- 
ing to  grief,  is  notoriously  a  result  of  disordered 
bodily  functions.  On  the  other  hand,  an  emotion 
may  resolve  itself  into  a  mood  which  persists  long 
after  the  transition. 

In  addition  to  the  general  reference  of  an  emo- 
tion to  its  "object,"  there  are  explicit  relationships 
or  groups  of  relationships  involved  in  emotions. 
These  relations  appertain  primarily  to  the  "object," 
but  are  essential  to  the  emotion.  Thus,  reverence 
and  contempt  involve  the  perception  or  conception 
of  the  object  as  superior  or  inferior  in  some  respect; 
usually  a  relation  of  the  sort  we  designate  as  per- 
sonal. Fear  involves  the  consciousness  of  the  ob- 
ject as  threatening  us;  hope,  as  possibly  attainable. 
Despair  permeates  the  object  which  is  ideated  as 
forever  sundered  from  our  possession.  Love  has 
been  defined  as  pleasure  plus  the  idea  (or  percep- 
tion) of  the  object  producing  the  pleasure;  this 
half-truth  brings  out  clearly  the  fact  to  which  we 


AFFECTIVE   CONTENT   OR    FEELING  203 

refer.  Mere  pleasure,  with  the  perception  of  the 
pleasing  object,  is  "  taking  pleasure  in  the  object," 
and  nothing  more;  but  given  the  proper  relation 
in  which  the  object  is  conceived  as  standing  to 
other  things,  the  emotion  may  become  one  of  warm 
approval;  and,  given  certain  relations  in  which  the 
object  is  conceived  to  stand  to  yourself,  the  emo- 
tion may  become  love. 

From  the  above  considerations  it  ought  to  be 
evident  that  any  analysis  of  the  emotions  which 
attempts  to  reduce  them  to  sensations  alone,  or  to 
sensations  and  affective  elements,  is  inadequate. 

7.  The  Classification  of  the  Emotions 

Many  attempts  have  been  made  in  the  past  to 
enumerate  the  principal  or  distinctive  emotions,  or 
to  tabulate  the  main  classes  into  which  all  emotions 
should  fall.  Success  has  crowned  none  of  these 
efforts;  they  have  not  even  gained  ground  from 
which  further  advance  may  be  made. 

The  varieties  of  emotion  are  actually  indefinite, 
and  practically  infinite  in  number.  One  emotion 
shades  off  into  another  by  slight  gradations,  and 
definite  delimitation  is  entirely  out  of  the  question. 

We  might,  indeed,  make  rough  divisions  of  emo- 
tions on  the  basis  of  hedono-algesis,  setting  those 


204  A    SYSTEM   OF   PSYCHOLOGY 

which  contain  painful  factors  over  against  those 
which  contain  pleasant.  Or  we  might  classify  on 
the  basis  of  desire  and  aversion.  A  distinction  has 
been  made  also  between  the  egoistic  or  self-re- 
garding, and  the  altruistic  emotions.  Many  other 
principles  of  classification  might  be  suggested,  but 
they  are  for  the  most  part  applicable  to  a  few  cases 
only,  and  they  are  all  practically  useless. 


CHAPTER   XV 

ACTION  AND  WILL 
i.  Action  in  General 

The  actions  of  which  the  human  body  is  ca- 
pable may  be  divided  usefully  into  two  classes: 
physiological  reflexes  and  consciousness-reflexes. 
The  first  class,  which  includes  the  actions  in  which 
consciousness  plays  no  essential  part,  is  but  in- 
directly of  interest  to  the  psychologist,  although  of 
extreme  importance  in  vital  function.  The  physi- 
ological reflex  may  be  produced  artificially  by  di- 
rect excitation  of  the  muscles  by  mechanical,  elec- 
trical, or  chemical  stimuli;  by  electrical  stimulation 
of  the  efferent  (motor)  nerves;  by  stimulation  of 
the  motor  cells  of  the  cortex  or  in  the  lower  cen- 
tres; and  perhaps  by  electrical  stimulation  of  cer- 
tain sensory  nerves.  The  exact  method  of  pro- 
duction of  the  natural  physiological  reflexes — such 
as  breathing,  heart-beat  and  arterial  dilation  and 
contraction,  intestinal  peristalsis,  glandular  secre- 
tion, pupillary  reflex — need  not  be  discussed  in  de- 
tail here.     In  the  case  of  the  pupillary  reflex  and 

265 


266  A    SYSTEM   OF   PSYCHOLOGY 

the  heart-beat,  the  activity  of  the  muscle  probably 
is  determined  largely  by  local  stimulation.  In  the 
case  of  breathing,  the  movements  are  wholly  ini- 
tiated by  nerve-currents  from  centres  in  the  cere- 
bellum. The  movements  of  swallowing  are  prob- 
ably brought  about  through  tactual  sensations 
(from  the  mouth)  which  excite  certain  nerve-centres, 
which  in  turn  excite  the  muscles  of  the  mouth  and 
gullet.  This  last  process  is  usually  in  part  a  con- 
sciousness-reflex. 

Actions  of  the  second  class  are  those  in  which 
consciousness  plays  an  important  role,  and  of  these 
four  types  may  be  distinguished:  sensational  re- 
flexes, or  sensory-motor  processes;  perceptual  re- 
flexes; ideational  reflexes,  or  ideo-motor  processes; 
and  voluntary  actions,  or  volitional  processes. 

In  the  sensational  reflex  the  consciousness  nec- 
essarily involved  is  a  sensation  merely.  Thus,  the 
hand  is  mechanically  retracted  upon  coming  into 
contact  with  a  hot  object;  the  mere  apprehension 
of  heat  is  sufficient  to  bring  about  the  reaction,  and 
the  apprehension  of  a  definite  hot  object  is  not  nec- 
essary, although  it  may  be  important  for  further 
action.  Winking  when  a  cinder  gets  in  the  eye,  is 
another  typical  sensational  reflex.  It  is  possible 
that  some  of  the  instinctive  actions  of  the  young 


ACTION   AND    WILL  267 

animal  may  belong  to  this  class.  The  first  suck- 
ing movement  of  the  babe,  for  example,  may  be 
conditioned  by  the  mere  tactual  sensations  aroused 
by  the  nipple  on  its  lips.  On  the  other  hand,  these 
actions  may  be  mere  physiological  reflexes,  or  they 
may,  for  aught  we  know,  depend  on  definite  per- 
ceptions. 

The  perceptual  reflex,  depending  on  apprehen- 
sion of  content  more  complicated  than  mere  sensa- 
tion, is  in  adult  life  more  important  than  the  mere 
sensational  reflex.  The  almost  unavoidable  wink- 
ing when  some  object  comes  quickly  toward  the 
vyv;  the  instinctive  putting  up  of  the  hand  to  ward 
off  or  catch  an  object;  the  flow  of  saliva  at  the 
smell  of  savory  food;  the  unintentional  mimicking 
of  an  acrobat  by  an  interested  spectator:  these  are 
typical  perceptual  reflexes. 

The  consciousness  immediately  antecedent  to  an 
action  may  not  be  of  presented  content  at  all,  but 
may  be  purely  ideational.  Action  under  such  con- 
ditions we  designate  as  ideational  reflex.  There 
are  many  cases  in  which  the  mere  thought  of  an 
act  brings  the  act  about.  Think  of  blinking;  of 
inhaling  deeply;  of  looking  behind  you;  of  yawn- 
ing; and  the  act  will  occur.  Thinking  of  the  re- 
sult of  the  act  may  be  sufficient  to  produce  it;    in 


268  A   SYSTEM   OF    PSYCHOLOGY 

many  cases,  thinking  of  a  word  is  accompanied  by 
the  speaking  of  the  word.  It  is  probably  true  that 
every  act  thought  of,  either  by  imaging  the  act  or 
by  imaging  the  result  thereof,  would  immediately 
"realize  itself"  if  there  were  not  other  factors  which 
interfere,  as  there  are  in  most  cases.  In  hypnosis 
it  is  probable  that  these  inhibitory  factors  are  sup- 
pressed, and  hence  the  ideas  communicated  to  the 
patient  have  a  chance  to  work  themselves  out  rather 
freely.  If  you  arouse  in  the  patient's  consciousness 
the  idea  of  a  horse,  contradictory  ideas  being  in 
abeyance,  he  will  produce  (as  nearly  as  his  bodily 
capacity  permits),  the  acts  characteristic  of  a 
horse. 

Certain  ideas  are  linked  with  certain  muscular 
and  glandular  activities,  although  they  are  not  the 
"ideas  of"  the  activities,  nor  "ideas  of"  the  re- 
sults. The  rather  complicated  ideational  content 
involved  in  the  notion  of  shame,  for  example, 
causes  relaxation  of  the  blood-vessels  in  such  a  way 
as  to  give  rise  to  a  blush.  The  idea  that  some  one 
has  treated  you  with  indignity  causes  the  changes 
which  are  felt  in  anger.  An  individual's  idea  of 
his  superiority  to  other  people  may  cause  him  to 
laugh  or  to  smile.  The  list  of  illustrations  might 
be  extended  indefinitely. 


ACTION    AND    WILL  2G9 

If  the  ideational  or  perceptual  reflex  is  compli- 
cated, i.  c,  if  there  are  a  number  of  details  of  action 
which  must  occur — some  simultaneously  and  some 
in  succession, — in  order  to  produce  a  definite  effect, 
as  in  walking  or  in  catching  a  ball,  but  if,  never- 
theless, the  group  of  activities  is  as  a  whole  depend- 
ent on  the  ideational  or  perceptual  fact,  as  in  the 
instances  mentioned,  the  combined  actions  are 
called  an  automatic  action.  If  an  automatic  action 
or  a  complicated  physiological  reflex  occurs  with- 
out its  having  been  learned,  it  is  said  to  be  instinc- 
tive. If  a  nestling  of  a  certain  age  is  thrown  into  the 
air,  it  will  fly;  this  first  flying  of  the  young  bird  is 
an  instinctive  action. 

Voluntary  action  is  an  ideo-motor  process,  but 
it  includes  more  than  the  mere  ideational  reflex. 
The  specific  differentia  of  the  voluntary  action  is 
desire  (or  the  opposite).  If  I  merely  think  of 
grasping  the  ink-well  which  stands  on  the  desk  be- 
fore me,  I  probably  shall  not  act  on  the  idea.  But 
if  I  desire  to  grasp  the  ink-well,  I  shall  grasp  it, 
unless  very  influential  counter-ideas  are  in  my  con- 
sciousness. 


270  A    SYSTEM   OF   PSYCHOLOGY 

2.  Volition 

We  have  indicated  above  that  volition  is  an  emo- 
tional state  which  involves  as  its  essential  features  an 
idea  of  a  future  condition  (anticipatory  idea)  with 
desire  of  (or  repugnance  to)  that  condition.  Not 
every  emotion  of  desire  (or  of  repugnance)  is,  how- 
ever, a  volition.  A  volition  is  an  emotion  of  desire1 — 
what  we  commonly  call  the  "desire  of"  something 
— in  the  absence  of  any  influential  contrary  idea 
and  conation.  If  you  see  some  choice  fruit  on  a 
tree  and  are  devising  means  by  which  you  may 
obtain  possession  thereof,  it  is  immaterial  whether 
we  say  you  desire  the  fruit,  or  that  you  will  to  get  it. 
But  if  you  entertain  the  idea  that  the  taking  of  the 
fruit  would  be  wrong,  or  suspect  that  the  owner 
is  near;  and  are  averse  to  the  act  or  its  conse- 
quences under  these  conditions;  and  if  the  aversion 
is  strong  enough  to  prevent  the  plucking  of  the  de- 
sired fruit;  we  should  call  your  content  desire,  and 
not  volition. 

The  total  content  of  consciousness,  where  it  is 
marked  by  opposing  ideas  and  conation,  is  called 


1  We  shall  speak  only  of  desire,  but  with  the  understanding 
that  the  same  remarks  apply  also,  mutatis  mutandis,  to  cases 
in  which  the  conative  factor  is  repugnance. 


ACTION    AND    WILL  271 

deliberation.  Put  in  active  terms,  you  deliberate 
over  (literally,  weigh)  the  desirable  and  undesirable 
possibilities  in  the  way  of  results  of  the  action.  One 
of  the  ideas  may  shortly  gain  the  ascendancy;  the 
other  either  fading  out  of  consciousness  or  losing 
its  conative  strength,  and  thus  the  content  become 
a  volition.  This  resolution  of  opposition  or  sub- 
ordination of  inhibitory  content,  by  which  the  mind 
"pulled  several  ways"  becomes  "confirmed  in  one 
direction"  is  called  decision  or  consent.  Some- 
times it  is  called  the  fiat. 

We  are  prone  to  think  of  deliberation  as  the  hesi- 
tation of  the  self  between  alternative  lines  of  possi- 
ble activity,  and  of  decision  as  the  active  choice 
by  the  self  of  the  one  or  the  other.  The  part  played 
by  the  self  in  deliberation  and  decision  may  be 
made  more  intelligible  later,  but  for  the  present 
it  is  sufficient  to  say  that  the  most  adequate 
conception  of  these  states  is  as  mere  matters  of 
content;  there  is  no  discoverable  force  —  as  of 
an  Ego  or  active  self — at  work  transforming  the 
content. 

It  is  not  necessary  that  deliberation  or  decision 
should  precede  or  form  a  part  of  volition.  The 
anticipatory  idea  may  be  offset  by  no  ideas  of  op- 
posing acts  or  of  restraints,  and  yet  the  act  which 


272  A   SYSTEM   OF   PSYCHOLOGY 

succeeds  may  be  strictly  voluntary.  The  boy  who 
sees  the  apple,  anticipates  with  desire  the  ingestion 
thereof,  and  takes  possession  of  it  without  a  thought 
of  owner's  rights  or  owner's  wrath,  performs  an 
action  as  truly  voluntary  as  if  he  deliberated  over 
the  situation  for  some  time,  and  came  to  a  decision 
with  an  experience  of  great  effort.  The  line  be- 
tween volition  and  desire  (emotion)  is  manifestly 
not  sharp,  nor  is  there  any  great  need  of  making  any 
sharp  distinction,  either  in  ethics  or  in  psychology. 
The  distinction  between  voluntary  action  and  ideo- 
motor  process  is  clear  for  the  extreme  cases,  but  the 
two  run  into  each  other  in  a  middle  ground,  where 
discrimination  is  impossible. 

The  desire  of  a  given  effect  is  called  the  motive 
of  the  desire  of  its  cause,  or  the  motive  of  the  volition 
based  on  the  latter  desire.  The  boy's  desire  or  will 
to  project  the  stone  through  the  window  may  be 
motived  by  a  desire  to  annoy  the  occupants  of  the 
house.  The  term  motive  is  applied  also  to  certain 
other  antecedents  of  an  act;  the  boy's  motive  for  the 
window-breaking  may  be  said  to  be  the  hatred  with 
which  he  regards  the  householder.  The  motiving 
emotion  has  always  desire  or  repugnance  as  a  con- 
stituent; it  is  because  the  boy's  hatred  for  the  man 
includes  as  its  prominent  factor  a  desire  to  see  him 


ACTION   AND   WILL  273 

degraded  in  some  way,  that  it  can  be  considered  a 
motive.  A  non-conative  emotion  cannot  motive 
any  desire  or  volition. 

3.  Volition  as  Activity 

There  is  one  method  of  describing  will,  which 
calls  a  volition  complete  only  when  to  the  antici- 
patory idea,  the  desire,  and  the  predominance  of 
these,  there  is  added  the  perception  of  the  realiza- 
tion of  the  idea.  Thus  when  I  thought  conatively 
of  picking  up  the  inkstand,  and  then  proceeded  to 
grasp  it,  I  completed  the  volitional  state  by  the 
perception  of  my  ringers  closing  around  the  glass. 
A  volition  regarded  from  this  point  of  view  is  more 
than  a  mere  content  or  combination  of  content; 
it  is  a  process,  and  cannot  be  represented  by  a  cross- 
section  of  consciousness;  it  finds  its  individuality 
not  in  any  specific  sort  of  content,  nor  in  any  specific 
combination  of  content  at  any  one  time,  but  in  a 
definite  sequence  of  states  of  content.  This  is  the 
doctrine  of  will  as  a  psychological  activity.  It 
differs  from  the  description  of  volition  we  have 
above  given  merely  in  the  application  of  terms. 
All  depends  on  the  choice  of  the  specific  features 
of  the  complicated  process  which  shall  be  designated 
by  the  term  volition. 


274  A   SYSTEM   OF   PSYCHOLOGY 

According  to  the  system  just  stated,  if  the  voli- 
tional process  does  not  issue  into  fulfilment  of  the 
idea,  but  stops  just  before  the  last  stage  because 
of  some  external  restraint,  it  is  called  determination, 
or  wish.  Thus,  I  determine  that  I  will  buy  some 
paper  when  I  next  go  down  town;  and  I  wish  to 
go  to  the  opera  to-night.  The  difference  between 
wish  and  determination  depends  on  the  anticipa- 
tory idea;  if  its  intellectual  factors  include  possibil- 
ity, the  resultant  state  is  determination;  if  possi- 
bility is  not  included,  it  is  merely  wish.  The 
distinction  between  volition  and  determination  is 
frequently  only  a  matter  of  point  of  view:  I  try  to 
catch  a  car,  but  miss  it;  from  the  point  of  view  of 
catching  the  car  my  content  was  mere  determina- 
tion, but  from  the  point  of  view  of  my  decision  to 
run  for  the  car,  the  state  was  volition.  It  is  not 
advisable  to  give  much  attention  to  the  activity  de- 
finition of  will,  or  to  the  problems  growing  out  of  it. 

4.  Automatic  Action 

In  descending  now  to  automatic  action,  we  mark 
two  stages;  first,  the  elimination  of  desire,  and,  sec- 
ond, the  elimination  of  the  anticipatory  idea. 

In  carrying  out  a  definite  series  of  activities  you, 
in  many  cases,  do  not  will  each  one;    even  when 


ACTION   AND    WILL  275 

each  act  is  separately  ideated  or  undertaken,  it  is 
not  desired.  In  an  earlier  chapter  we  have  spoken 
of  the  spreading  of  the  desire  from  the  effect  or  end 
to  the  causes  or  means;  but  although  this  does  occur 
in  some  cases,  it  is  not  essential.  Thus,  if  I  desire 
to  get  a  book  from  the  library  across  the  street,  I 
get  up,  put  on  my  hat,  go  across  and  ring  the  bell 
of  the  elevator  in  the  library,  so  performing  a  num- 
ber of  acts  which  are  ideationally  initiated,  but 
which  individually  are  comparatively  free  from  any 
appetitive  factor.  At  the  same  time,  in  the  course 
of  getting  my  book  I  have  performed  several  acts 
which  are  not  even  consciously  initiated,  although 
they  are  like  the  ones  just  mentioned,  in  that  they 
might  be  initiated  ideationally.  Walking,  for  ex- 
ample, can  be  done  by  voluntarily  placing  the  legs 
and  body  in  the  requisite  successive  positions,  but 
usually  it  proceeds  without  either  the  desire  or  the 
idea  of  these  positions.  So  it  is  with  opening  the 
door,  avoiding  a  car,  catching  my  hat  just  as  the 
wind  lifts  it  from  my  head,  etc.  These  are  all  acts 
which  may  be  involved  in  the  total  action  of  getting 
the  book,  and  not  only  may  take  place  mechanically 
in  the  proper  order  as  if  they  were  premeditated 
severally,  but  actually  are  more  efficiently  performed 
when  they  are  mechanical. 


276  A    SYSTEM   OF   PSYCHOLOGY 

If  the  movements  essential  to  the  carrying  out  of 
a  series  of  activities  are  not  perfectly  uniform,  but 
require  variation  to  fit  the  environment  (as  in  walk- 
ing on  uneven  surfaces,  turning  corners,  stepping 
over  gutters,  etc.)  these  variations  are  introduced 
as  perceptual  reflexes;  you  see  the  gutter,  for  ex- 
ample, and  the  appropriate  modification  of  the 
action  of  the  muscles  occurs  without  any  further 
conscious  intervention.  The  whole  series  of  walk- 
ing movements  may  take  place  in  the  same  way:  my 
idea  of  getting  the  book  may  be  succeeded  by  or 
include  no  idea  of  locomotion;  the  mere  perception 
of  my  local  situation  may  start  my  legs  moving. 

An  automatic  act  may  be  considered  as  a  series 
of  reflexes,  perceptual,  sensational,  or  physiological, 
in  which  each  completed  detail  serves  as  a  stimulus 
for  the  next.  Thus,  in  walking,  the  shifting  of  the 
weight  to  the  left  leg  may  be  the  stimulus  for  the 
extension  of  the  right  leg,  and  so  on :  these  two  acts 
are  themselves  complex,  and  the  series  of  muscular 
contractions  which  produces  them  are  connected 
in  a  reflex  way;  when  one  is  completed  or  reaches 
a  certain  stage,  it  sets  off  the  next  one.  So,  the 
whole  process  repeats  itself  automatically  and  is 
continued  until  inhibited  by  a  new  idea,  perception, 
or  sensation.     It  is  probable  that  every  function- 


ACTION   AND   WILL  277 

ally  connected  series  of  acts  tends  to  pass  in  succes- 
sion from  perceptual  to  sensational  and  physiologi- 
cal reflex-types,  as  regards  the  initiation  of  the 
particular  acts. 

5.  Instinctive  Action  and  Learning 

The  difference  between  an  instinctive  action  and 
an  automatic  action  or  complicated  reflex  whose 
sequences  and  combinations  are  acquired,  is  simple 
in  theory,  although  in  practice  discrimination  is  not 
always  easy.  The  action  of  a  young  bird's  wings 
in  its  first  flight  are  instinctive — it  never  learned 
these  actions.  Your  actions  in  waltzing  are  ac- 
quired— nature  may  have  endowed  you  with  the 
capacity  for  the  essential  movements  of  the  feet  and 
legs,  but  you  had  to  learn  the  right  combinations 
laboriously.  The  co-ordinating  wing-movements 
of  the  fledgling  may  be  initiated  by  the  perceptions 
aroused  when  the  bird  first  finds  itself  in  the  air, 
or  they  may  be  simply  complicated  physiological 
reflexes.  On  the  other  hand,  the  conclusion  that 
either  of  these  suppositions  is  true  is  at  least  pre- 
mature. It  is  possible  that  the  flying  may  be  initi- 
ated by  ideas  or  even  by  the  desire  of  flight.  Other 
instances  of  complex  actions  which  are  instinctive 
— i.  c,   not  acquired, — are   the   feeding   of  young 


278  A    SYSTEM   OF   PSYCHOLOGY 

birds  and  young  mammals,  and  the  first  creeping, 
walking,  and  talking  of  young  children.  Our 
adult  activities  are  based  throughout  on  instincts, 
but  in  the  development  of  these  activities  the  ac- 
quired part  comes  to  overshadow  the  instinctive. 
The  turning  of  door-knobs,  buttoning  of  coats, 
playing  of  violins,  manipulating  of  complicated 
scientific  instruments,  the  use  of  knives  and  forks, 
and  so  on  ad  Infinitum,  are  actions  initiated  by  the 
visual  or  tactual  perception  of  certain  objects;  yet 
the  combinations  of  muscular  processes  necessary 
to  the  accomplishment  of  these  actions  have  been 
learned  in  past  experience. 

Learning,  in  the  domain  of  action,  is  in  every  case 
the  combining  of  simple  or  relatively  simple  activi- 
ties which  primarily  occur  instinctively  or  acci- 
dentally, for  the  accomplishment  of  something 
which  none  of  the  simple  acts  could  compass.     Such 

learning  may  proceed  in  one  of  three  ways: 

(1)  The  combination  may  be  entirely  acciden- 
tal. The  child  may  by  chance  make  the  "th" 
sound  and  associate  the  sound  with  the  proper  po- 
sition of  the  tongue  and  lips.  The  dog  confined 
in  the  yard  noses  frantically  at  the  gate  until  acci- 
dentally he  trips  the  latch.  If  the  animal  is  thus 
fortunate  several  times  he  may  form  an  association 


ACTION    AND   WILL  279 

between  the  percept  of  the  latch  and  the  appropri- 
ate action. 

(2)  Imitation.  A  child  may  learn  a  new  pur- 
posive combination  of  movements  at  one  stroke  by 
seeing  the  action  performed  by  somebody  else. 
A  peculiar  hop  or  skip,  the  winding  of  a  clock  or 
mechanical  toy;  the  buttoning  of  a  garment;  may 
be  new,  but  performed  fairly  well  the  first  time. 
By  far  the  greater  number  of  actions  called  imi- 
tative are,  however,  combinations  of  movement 
processes  already  learned,  applying  to  specific  ob- 
jects or  purposes.  Almost  all  of  the  imitative 
bodily  postures  and  gestures  fall  into  this  class. 
Such  activities  as  the  putting  on  of  clothes,  eating 
with  forks  and  spoons,  and  the  great  mass  of 
practical  activities  in  general,  are  learned  slowly, 
and  can  be  called  imitative  only  if  you  wish  to 
apply  that  term  to  every  non-instinctive  action. 

In  learning  by  imitation,  strictly  so-called,  the 
individual  sees  an  act  performed  which  he  recog- 
nizes as  a  combination  of  certain  more  elementary 
processes  of  which  he  is  already  master,  and  then 
proceeds  to  perform  this  group  of  actions  in  the 
specific  order  and  combination,  for  the  first  time. 
An  act  which  is  repeated  by  imitation  must  be 
one  which  the  subject  has  previously  performed. 


280  A   SYSTEM   OF   PSYCHOLOGY 

Imitation  therefore  presupposes  a  high  state  of 
development  "mentally"  and  muscularly.  All  the 
components  of  the  imitative  act  must  be  under 
ideational  control;  must  be,  in  short,  capable  of  be- 
ing voluntarily  performed.  If  a  child  can  say  shoo 
and  gar  volitionally  or  as  ideo-motor  reflexes,  he  can 
succeed  tolerably  well  in  imitating  your  utterance 
of  "sugar."  But  if  the  child  has  not  learned  to 
say  the  word  or  the  two  syllables  separately  he  can- 
not imitate  it.  It  is  possible,  however,  that  if  he  can 
voluntarily  say  "  thu,"  he  may  recognize  a  similar- 
ity of  that  sound  to  "su"  and  make  the  substitution. 

Imitation  has  really  a  small  place  in  the  field  of 
learning.  In  most  cases  it  applies  to  the  already 
learned.  The  mere  incentive  to  learn  furnished 
by  our  observation  of  what  others  actually  do 
ought  not  to  be  called  imitation :  the  term  indicates 
either  a  perceptual  or  ideational  reflex,  in  which  the 
essential  percept  or  idea  is  of  a  similar  act  performed 
by  another  person. 

(3)  Conceptual  analysis.  At  a  higher  stage  of 
"mental"  development,  the  individual  is  able  to 
make  new  movement-combinations  by  a  process  of 
analysis.  A  certain  situation  is  presented,  which 
requires  a  number  of  movements  in  combination 
and  succession,  e.  r/.,  the  operation  of  a  typewriter. 


ACTION   AND    WILL  281 

The  beginner  may  without  assistance  discover  the 
functions  of  the  keys,  the  spacer,  and  the  shift,  and 
proceed  to  combine  these  functions;  to  alternate 
characters  and  spaces,  to  hold  down  the  shift  while 
printing  a  capital,  and  to  hold  down  the  shift  and 
spacer  while  underlining  or  accenting.  In  all  this 
combination  there  need  be  neither  accident  nor  imi- 
tation, although  all  the  movements  here  combined 
are  put  within  the  individual's  power  by  instinct, 
and  accident,  assisted  by  imitation.  Once  learned, 
the  combination  becomes  automatic,  if  the  operator 
becomes  in  any  wise  expert. 

Although  for  aught  we  know  the  lower  animals 
may  "learn"  actions  altogether  without  the  aid  of 
consciousness,  man  learns  chiefly  through  volition. 
But  the  terminus  of  the  learning  process  is  that  con- 
dition of  efficiency  in  which  volition,  ideas,  and 
other  content  of  consciousness  are  eliminated  as 
far  as  possible  from  the  sequences  of  the  action. 

6.  Habit 

One  of  the  most  important  features  in  the  de- 
velopment of  action  is  habit.  Once  a  volition  has 
occurred,  it  is  easier  for  it  to  occur  again.  It  may 
occur  the  first  time  after  "hanging  fire"  a  long  time 
in  the  "strife"  of  opposing  ideas,  but  next  time  the 


282  A    SYSTEM   OF   PSYCHOLOGY 

strife  is  shorter.  With  each  repetition  the  process 
is  accelerated  and  made  easier,  until  finally  the  idea 
alone  will  produce  the  action,  and  we  have  the  first 
step  toward  automatism.  If  a  series  of  actions 
occurs  habitually  in  the  same  order,  after  suf- 
ficient time,  not  only  the  essential  desires  and  voli- 
tion, but  the  ideas  as  well,  will  be  eliminated  and  the 
series  once  started  will  unroll  mechanically  unless 
modified  by  new  sensations;  automatism  will  be 
complete. 

Habitual  repetition  may  modify  the  action  in 
another  way.  The  sensory  content  which  at  first 
aroused  the  anticipatory  idea  and  desire  may  become 
able  to  do  the  work  alone,  by  the  progressive 
elimination  of  the  two  factors  mentioned,  thus  giv- 
ing rise  to  the  acquired  reflex.  The  sight  of  the 
letter  put  into  your  hands  may  be  followed  by  the 
opening  of  the  letter,  even  when  you  have  neither 
idea  nor  desire  of  the  act  or  its  consequences. 

The  instinctive  reflex  has  been  called  an  inborn 
habit.  "Whether  the  tendency  to  act  in  a  certain 
way  is,  or  is  not,  the  result  of  the  habits  formed  by 
preceding  generations,  the  instinct  is  certainly  on 
the  exact  plan  of  the  habitual  action,  and  can  be 
understood  only  by  beginning  with  the  latter  and 
working  down   to   the   former.     Yet   the  order  in 


ACTION   AND    WILL  283 

analysis  is  not  necessarily  the  order  in  history,  and 
we  need  assume  nothing  as  to  the  mechanism  and 
process  in  the  development  of  the  instinct.  So  far 
as  any  one  knows,  tendencies  to  think  and  feel  may 
just  as  well  be  inborn  as  may  tendencies  to  act,  and 
hence  we  must  be  cautious  in  classifying  any  given 
act  of  the  young  animal  as  reflex,  ideo-motor,  or 
voluntary. 

Habit  is  an  enormous  factor  in  our  psycho-physi- 
cal existence,  and  has  received  its  due  attention 
from  the  psychologists.  But  as  yet  no  explanation 
has  been  found  for  the  method  of  operation  of 
habit.  The  building  up  of  habit  has  been  likened 
to  the  formation  of  channels  by  streams  of  water 
and  to  the  wearing  of  paths  by  successive  footsteps 
which  erode  the  soil  deeper  and  deeper.  The  laws 
of  habit  are  sometimes  stated  in  terms  of  "brain- 
paths,"  but  we  must  remember  that  this  form  of 
statement  is  merely  a  carrying  out  of  the  analogy 
just  mentioned,  and  means  little  in  physiology. 
All  we  can  do  at  present  is  to  state  the  facts  psycho- 
logically, and  admitting  that  they  have  their  physio- 
logical conditions,  keep  a  sharp  lookout  for  what 
may  be  discoverable  concerning  these  conditions. 


284  A   SYSTEM   OF   PSYCHOLOGY 

Note 

The  "motor  tendency  of  thought"  may  be  ex- 
hibited in  the  case  of  a  normal  subject  by  any  of  the 
usual  means  for  recording  "automatisms."  For 
instance,  have  the  subject's  hand  resting  on  a  plan- 
chette,  or,  better  still,  on  a  glass  plate  resting  on 
three  steel  balls  which  roll  on  a  second  plate,  the 
upper  plate  having  attached  to  it  a  pencil  which 
bears  upon  a  strip  of  paper.  Have  a  screen  so 
interposed  that  the  subject  cannot  see  his  hands  nor 
the  pencil  and  paper.  Let  him  see  you  trace  a  line 
on  the  wall  in  front  of  him,  or  hear  you  describe  such 
a  line  verbally.  In  nearly  every  case  the  subject's 
hands  will  move,  as  shown  by  the  pencil  record,  in 
a  way  corresponding  to  the  line. 

Buckle  a  strap  around  the  subject's  head  (over 
the  top  of  the  head  and  under  the  chin),  and  fasten 
to  the  strap  on  top  of  the  head  a  wooden  point. 
Let  the  subject  stand  (with  eyes  closed)  under  a 
sheet  of  smoked  paper  supported  at  one  edge  and 
resting  on  the  wooden  point.  Tell  the  subject  to 
stand  perfectly  still,  and  mention  to  him  interesting 
objects  actually  or  suppositionally  lying  in  certain 
directions  from  him,  and  he  will  be  found  to  move 
in  the  designated  direction,  or  the  opposite,  accord- 
ing to  the  nature  of  the  object. 


CHAPTER  XVI 

THE  SELF,  OR  EMPIRICAL  EGO 

One  of  the  most  obvious  distinctions  in  the  con- 
tent of  experience  is  that  between  the  self  and  the 
not-self;  between  the  mc  and  the  remainder  of  the 
world.  Several  different  distinctions  have,  how- 
ever, been  described  in  terms  of  self  and  not-self,  and 
the  terms  are  even  at  the  present  day  used  in  a 
variety  of  significations.  Sometimes  the  terms 
self  and  not-self  have  been  applied  to  an  assumed 
substantial  soul,  and  the  world  of  experience  re- 
spectively; sometimes  to  "mind"  and  its  contents; 
sometimes  to  the  content  of  consciousness  and  an 
assumed  external  reality.  We  are  referring  here  to 
none  of  those  distinctions.  For  Psychology,  the 
self  and  the  not-self  are  both  content:  with  a  self 
and  a  not-self  that  are  not  content  we  have  practi- 
cally nothing  to  do,  no  matter  what  may  be  our  ar- 
ticles of  faith  on  the  question  of  the  reality  of  these. 

We  have  found  in  the  content  nothing  but  sen- 
sations, relations,  and  feelings,  and  possibly  images. 
If  this  is  a  complete  list  of  the  kinds  of  content,  then 

the  self  or  "me"  is  made  up  of  these  factors,  or  at 

285 


286  A    SYSTEM   OF   PSYCHOLOGY 

least  can  be  resolved  by  analysis  into  them.  We 
cannot  rigidly  prove  that  there  is  not  an  objective 
self  sai  generis  which  pervades,  accompanies,  or  is 
somehow  experienced  along  with  the  general  con- 
tent. All  that  we  really  need  to  say  is,  that  no  one 
has  been  able  to  demonstrate  such  a  factor  in  con- 
tent. When  you  analyze,  the  self  reduces  to  the 
forms  of  content  we  have  described,  and  no  residue 
can  be  detected.  The  self  must  then  be  described 
either  as  certain  factors  of  content  in  combination; 
or  as  a  certain  form  of  combination  of  content,  in 
simultaneity  and  succession;  or  as  both.  How  large 
a  part  the  form  of  combination  of  content  plays 
in  the  self  is  a  problem  too  difficult  to  be  taken  up 
here,  and  is  not  important  for  our  purposes.  Under 
any  plan  of  description  the  self  is  wholly  content. 
The  first  elements  we  notice  when  we  attend  to 
the  self  and  attempt  to  analyze  it,  are  bodily  sen- 
sations. Sensations  of  warmth,  cold,  and  pressure 
from  the  surfaces,  with  sensations  from  the  joints, 
muscles,  and  viscera;  combine  into  a  mass  which 
is  constantly  present,  even  in  the  lighter  phases  of 
sleep.  This  mass  is  a  part  of  the  "me"  in  a  pro- 
found sense.  On  the  other  hand,  certain  other  sen- 
sations from  the  same  organs  are  not  fused  with 
this  mass,  but  stand  off  from  it  as  something  for- 


THE    SELF,    OR   EMPIRICAL   EGO  287 

eign.  "While  we  can  make  no  very  definite  state- 
ment on  this  point,  it  is  probable  that  anything 
which  gives  a  sensation  a  distinctive  position,  as,  for 
example,  relatively  high  intensity,  sharp  spatial  or 
temporal  limits,  or  strong  associative  connection, 
tends  to  separate  it  from  the  vaguer  mass  which  is 
at  the  foundation  of  the  self. 

The  feelings  are  the  constituents  of  the  self  which 
are  next  in  importance  to  the  sensations,  and  they 
are,  apparently,  without  exception  involved  in  the 
self.  However  you  may  feel — whatever  feelings 
you  may  "have" — these  feelings  are  a  part  of  you; 
to  name  them  is  to  describe  in  part  the  sort  of  self 
you  are — or  "have" — at  that  specific  time.  The 
emotions,  which  we  have  concluded  are  masses  of 
unanalytically  apprehended  sensations  and  feelings, 
are  necessarily  also  factors  in  the  self.  This  fact 
was  understood  by  various  psychologizing  philos- 
ophers long  before  the  present  theory  of  the  emo- 
tions was  elaborated.  The  emotions,  they  said,  are 
modifications  of  the  self,  and  hence  of  a  different 
order  from  "perceptions"  and  "ideas." 

The  self,  furthermore,  contains  all  the  other  sen- 
sations (and  relations)  which  make  up  the  per- 
ceived human  body.  The  visual  and  auditory 
"sensations  of  the  body"  are  included  without  re- 


288  A   SYSTEM  OF   PSYCHOLOGY 

spect  to  their  distinctness  or  sharp  definition.  The 
body,  in  short  (as  an  experienced  fact,  not  as  a 
materialized  supposition),  is  fundamentally  the  self. 
A  striking  demonstration  of  the  truth  of  this  state- 
ment is  found  in  the  uniformity  with  which  all 
naturally  developed  religions  which  assume  a  per- 
sistence of  the  self  after  death  ascribe  to  it  a  body 
of  some  sort. 

Psychic  individuality,  or  self-hood,  means  thus 
more  than  mere  capacity  for  experience.  It  means 
the  existence  of  a  specific,  although  complex,  con- 
tent which  is  persistently  present;  which,  although 
it  changes  its  total  character,  changes  slowly;  and 
which  hence  is  the  standard  against  which  all  other 
content  is  measured.  The  self  forms  accordingly 
the  basis  for  the  perceived  continuity  of  the  ever- 
changing  content.  Its  rhythmic  variations  with 
the  solar  day  and  the  physiological  condition  serve 
as  the  clock  of  consciousness.  When  hungry,  the 
idea  of  the  normal  steps  for  obtaining  food  are 
brought  up  through  normal  association.  In  the 
morning,  the  recurring  associations  with  the  morn- 
ing state  of  the  self  bring  up  the  proper  ideas  for 
that  time  of  day  almost  unfailingly.  The  intricate 
system  of  associative  nexus  which  bind  past  experi- 
ences   together   and    make   our   relatively   orderly 


THE   SELF,    OR  EMPIRICAL  EGO  289 

mental  life  possible  might  be  controlled  in  some 
other  way,  but  as  a  matter  of  fact  they  arc  con- 
trolled by  the  particular  associations  of  this  bodily 
self  with  the  other  factors  in  the  manifold. 

The  self  is  by  no  means  exhausted  by  the  body 
and  the  feelings.  Many  things  to  which  the  body 
stands  in  a  particularly  intimate  relation  are  ab- 
sorbed into  the  self.  Family,  business,  and  social 
relations,  for  example,  tend  to  become  relations 
within  the  self. 

The  mass  of  habitually  experienced  content  is  the 
self.  "Thoughts"  are  in  some  respects  more  im- 
portant than  percepts.  "As  a  man  thinketh,  so  is 
he,"  is  trite  but  largely  true.  The  phases  of  per- 
sonality which  are  essentially  habitual  ways  of 
thinking,  or  habitual  sorts  of  thought  content,  we 
usually  designate  by  the  term  "character."  But 
the  habitual  trains  of  thoughts  are,  as  we  know,  de- 
termined to  a  large  extent  by  the  feelings,  and  not 
only  by  mere  feelings,  but  by  emotional  complexes. 
So  that  in  the  healthy  individual,  self,  including 
character,  is  a  rather  coherent  mass  of  content. 

In  many  cases  an  apparently  normal  individual 
possesses  a  double  character.  The  church-going 
business  man,  on  Sunday,  for  example,  may  really 
think  admirable  thoughts,  which  may  be  allowed 


290  A   SYSTEM  OF  PSYCHOLOGY 

to  find  expression  in  suitable  action.  On  other 
days  he  thinks  only  of  business,  and  his  actions 
are  quite  at  variance  with  his  Sunday  doings.  It  is 
quite  probable  that  he  builds  up  a  double  set  of 
sensational  selves,  too,  one  of  which  is  associated 
with  each  of  the  thought-complexes.  The  evidence 
for  this  assumption  is  found  in  the  fact  that  his 
facial  and  bodily  expressions  change  with  his  change 
of  character,  and  give  grounds  for  suspecting  more 
profound  organic  modifications.  Certainly,  he  has 
two  sets  of  emotional  habits.  He  really  is  not  a 
hypocrite,  in  an  ethical  sense,  but  is  a  diseased  per- 
son, a  monster  with  two  selves. 

There  are  an  indefinite  number  of  possible  prin- 
ciples of  bifurcation  of  the  self,  and  these  bifurca- 
tions may  be  incipient  or  thorough-going,  that  is, 
they  may  affect  only  the  habits  of  thought,  or  may 
affect  the  bodily  sensations.  A  man  may  be  pure- 
minded  at  certain  times,  and  lewd  at  others;  he 
may  be  a  buoyant  optimist  and  a  downcast  pessi- 
mist; and  so  on  ad  infinitum.  And  any  of  these 
divisions  of  character  may  by  the  gradual  forma- 
tion of  associations  become  a  cleavage  affecting 
practically  the  whole  personality.  There  may  be 
three  of  these  fractional  personalities,  or  even  more, 
in  a  given  case. 


THE   SELF,    OR   EMPIRICAL   EGO  291 

It  is  probable  that  none  of  us  are  completely  free 
from  the  taint  of  divided  personality,  but  most  of 
us  need  not  fear  any  disastrous  developments.     The 
dangerous  cases  are  those  in  which   one  side  of 
the  character  has  been  long  repressed,  but  is  still 
smouldering.     The  individual,  for  instance,  gives 
rein  usually  to  the  moral  member  of  his  team  of 
selves,  and  allows  the  lewd  character  to  express  itself 
only  at  the  infrequent  times  when  he  thinks  he  is 
safe  from  the  observation  of  his  associates.     In  this 
case,  some  change  in  the  bodily  condition,  deeply 
stirring  the  whole  self,  gives  the  repressed  self  its 
chance,  and   flaring  up,  perhaps  suddenly,  it  be- 
comes  dominant.     In   extreme   cases   the   sets   of 
ideas  constituting  the  character  side  of  the  previously 
dominant  self,  and  the  other  groups  of  ideas  asso- 
ciated with  these,  are  completely  lost,  and  hence  the 
patient  not  only  evinces  a  seemingly  new  person- 
ality, but  actually  loses  the  memory  of  years  of  his 
life.     These  sudden  changes  are  called  alterations 
of  personality,  and  in  the  cases  where  there  is  re- 
peated change  from  one  personality  to  the  other 
or  others,  the  terms  alternation  of,  personality  and 
alternating   personality  are  applied.     These  cases 
will  be  further  discussed  in  Chapter  XIX. 


CHAPTER  XVII 

THE  DEGREES  OF  CONSCIOUSNESS 
i.  Consciousness,  Attention,  and  Vividness 

Up  to  this  point  we  have  restricted  our  discussion 
as  far  as  possible  to  the  objects  of  which  we  are  con- 
scious and  the  behavior  of  these  objects,  that  is  to 
say,  to  the  items  and  processes  of  content.  Now  we 
must  undertake  the  seemingly  impossible  task  of 
examining  consciousness  itself.  How  it  is  possible 
to  examine  consciousness,  and  in  what  consists  the 
operation  which  we  thus  designate,  are  problems 
which  are  beyond  the  scope  of  the  present  under- 
taking. As  a  matter  of  fact  we  do  study  or  discuss 
consciousness,  whether  directly  or  indirectly. 

For  practical  reasons  we  have  somewhat  antici- 
pated the  discussion  of  kinds  of  consciousness,  and 
have  entertained  the  possibility  of  distinguishing 
two  kinds;  the  consciousness  of  content  "present" 
(intuition)  and  the  consciousness  of  content  not 
"present"  (imagination).  The  fact  that  neither  of 
these  can  exist  separately,  but  that  what  we  really 
find  is  consciousness  of  a  content  partly  present  and 

partly  not  present,  is  no  obstacle  to  the  analytical 

292 


THE    DEGREES   OF   CONSCIOUSNESS  293 

consideration  of  the  two  kinds,  and  establishes  no 
presumption  against  the  value  of  such  consideration. 
The  case  is  precisely  the  same  as  in  the  discussion  of 
sensation  as  such.  At  the  present  time,  however, 
there  seems  to  he  no  practical  advantage  in  the 
lengthy  discussion  of  these  or  other  hypothetical 
sorts  of  experience. 

Consciousness  varies  in  degree.  One  extreme  of 
the  range  of  variation  is  commonly  known  as  a  high 
degree  of  attention,  or  concentration  of  attention. 
The  other  extreme  is  inattention,  to  which  the 
term  subconsciousness  is  also  applied.  The  general 
designation  of  attention  is  thus  given  only  to  the 
higher  degrees  of  consciousness.  If  referred  to  the 
content,  the  degrees  of  consciousness  are  degrees 
of  vividness,  which  is  sometimes  called  clearness. 
Thus,  to  say  that  I  attend  to  a  sensation  or  percept 
is  equivalent  to  saying  that  the  sensation  or  per- 
cept is  vivid.  The  content  not  attended  to  is  non- 
vivid.  In  a  somewhat  better  use  of  the  term  we 
speak  of  a  high  degree  of  vividness  and  a  low  degree 
of  vividness  in  the  two  cases  mentioned.  Whether 
any  content  may  properly  be  said  to  be  not  vivid 
at  all  is  a  matter  which  we  will  consider  later. 

The  term  attention  properly  signifies  a  condition 
or  state  of  consciousness  itself.     Sometimes  it  is  ap- 


294  A    SYSTEM   OF   PSYCHOLOGY 

plied  to  a  certain  content  as  well.  When  I  attend 
to  a  sound,  I  am  conscious  of  an  adjustment  of 
head,  and  possibly  of  a  change  in  the  tension  of  the 
muscles  of  the  middle  ear.  When  I  attend  to  a 
light,  I  am  conscious  of  an  adjustment  of  the  inter- 
nal and  external  muscles  of  the  eye.  In  addition, 
in  both  cases,  there  are  sensations  of  strain  from 
the  muscles  of  other  parts  of  the  body;  the  chest, 
the  face,  perhaps,  also,  the  arms  and  legs.  All  these 
factors  are  sometimes  included  under  the  head  of 
attention.  Again,  the  motor  adjustments  as  ap- 
prehended by  another  individual  are  referred  to  by 
the  name  attention.  A  dog,  for  example,  is  said  to 
"attend"  to  an  object  when  his  sense-organs  are  so 
adjusted  as  to  give  him  the  best  condition  for  stimu- 
lation by  the  object,  although  we  make  no  assump- 
tions as  to  the  dog's  consciousness.  The  student 
may  later  find  it  difficult  to  escape  falling  into  con- 
fusion on  account  of  the  varying  uses  of  the  term 
by  different  authors. 

The  total  content  of  consciousness  at  any  given 
moment  is  conventionally  spoken  of  as  the  "field 
of  attention"  or  "field  of  consciousness."  It  is 
likened  to  the  visual  field,  i.  c,  to  the  mass  of  visual 
content  "spread  out"  before  the  eye  at  any  given 
time.     This  analogical  treatment  is  quite  defensi- 


THE    DEGREES   OF   CONSCIOUSNESS  295 

hie,  since  we  may  consider  visual  content  as  typical 
of  all  content.  In  this  field  of  consciousness,  as 
spatially  analogized,  we  may  represent  the  highest 
degrees  of  vividness  at  the  centre,  and  the  lesser  de- 
grees by  zones  at  different  distances  therefrom. 
The  centre  of  this  conventionalized  field  is  called 
the  "  focus,"  and  the  most  remote  portions  are  called 
the  "fringe"  of  consciousness. 

A  question  which  naturally  arises  at  this  point  is 
as  to  the  number  of  discernible  degrees  of  atten- 
tion. Are  there  three  degrees:  a  focus,  a  fringe, 
and  an  intermediate  region  ?  Or  are  there  only  two 
grades,  focal  and  non-focal  ?  or  are  there  four,  five, 
or  more  grades?  This  question  may  be  left  open 
for  the  present,  as  no  adequate  means  of  determining 
the  number  of  degrees  has  yet  been  found. 

2.  Vividness  and  Intensity 

Vividness  is  sometimes  confused  with  intensity. 
Hence  it  is  necessary  to  distinguish  carefully  be- 
tween the  two,  as  well  as  to  consider  their  connec- 
tions. Suppose  you  are  talking  to  a  friend,  while 
a  large  clock  is  ticking  loudly  on  the  mantel.  The 
clock,  we  will  suppose,  is  in  your  range  of  vision, 
and  the  ticking  is  plainly  audible,  but  neither  is  of 
much  consequence  in  your  total  content  until  your 


296  A   SYSTEM   OF   PSYCHOLOGY 

friend  remarks  "what  a  curious  old  clock!"  Im- 
mediately the  clock  (visual  and  auditory)  becomes 
vivid,  and  the  features  and  voice  of  the  person  be- 
come reduced  in  vividness.  Has  the  intensity 
(loudness)  of  the  ticking,  or  the  brightness  of  the 
visual  sensations  increased?  Not  to  any  appreci- 
able extent;  neither  has  the  loudness  of  the  speaker's 
voice  decreased,  nor  the  intensity  of  the  visual  pres- 
entation of  his  features  waned.  The  "  focus  of 
consciousness"  has  shifted,  or  rather,  the  impres- 
sions have  shifted  as  regards  the  focus,  but  changes 
in  intensity,  if  they  occur,  are  purely  accidental,  and 
are  due  to  such  factors  as  change  in  position  of  the 
eyes,  or  in  the  tension  of  the  ear-muscles.  (We  are 
not  considering,  of  course,  the  possible  actual  changes 
in  the  physical  intensity  of  the  voice,  or  in  the  il- 
lumination of  the  room.) 

Attempts  have  been  made  to  determine  the  ef- 
fects of  vividness  on  intensity  of  sensation,  with  re- 
sults which  are  seemingly  contradictory,  but  really 
harmonious.  The  characteristic  method  of  exper- 
iment is  to  find  what  intensity  of  a  sensation  of  given 
quality  will  be  judged  equal  to  the  intensity  of  a 
sensation  of  the  same  quality  which  immediately 
precedes  or  follows  it,  when  the  subject  "gives  full 
attention"  to  one  of  the  pair,  and  is  "distracted" 


THE    DEGREES   OF  CONSCIOUSNESS         297 

somewhat  from  the  other  by  accompanying  sensa- 
tions, or  by  performing  mental  labor,  as  adding  or 
multiplying,  or  repeating  verses.  The  other  con- 
ditions are  kept  as  constant  as  possible  for  both  sen- 
sations. 

Some  experiments  have  apparently  shown  that  a 
sensation  to  which  full  attention  is  given,  is  judged 
equal  to  a  sensation  which  is  less  vivid,  when  the 
intensity  of  the  more  vivid  sensation  is  slightly  less 
than  that  of  the  less  vivid  one.  Other  experiments 
have  shown,  on  the  other  hand,  exactly  the  reverse. 
Hence  we  have  had  some  experimenters  claiming 
that  attention  to  a  sensation  increased  the  intensity 
while  others  have  claimed  that  the  attention  de- 
creased the  intensity. 

As  a  matter  of  fact,  these  experiments  have  no 
bearing  at  all  on  the  question  of  the  relation  of  in- 
tensity and  vividness.  They  simply  bear  on  the 
judgment  of  relative  intensity,  which  is  a  different 
matter.  Similar  results  may  be  obtained  in  the  case 
of  judgment  of  size,  as  when  two  squares  are  com- 
pared;  and  in  the  case  of  judgments  of  quality. 

That  intensity  affects  vividness  we  cannot  deny. 
A  rapid  change  in  the  intensity  of  any  sensation — 
either  increase  or  decrease — tends  to  bring  it  to  the 
focus  of  attention.     Of  several  sensations  or  sen- 


298  A   SYSTEM  OF   PSYCHOLOGY 

sation-complexes,  the  most  intense  will  probably 
have  strongest  claim  on  the  attention,  other  things 
being  equal.  Other  factors  are,  however,  so  much 
more  important  that  little  effect  is  produced  by  the 
mere  intensity. 

3.  Factors  Determining  Vividness 

A.  Sensational  Factors. — Intensity,  we  have  just 
considered.  Extensity  and  area  may  operate  in 
the  same  way.  The  larger  tends  to  obscure  the 
smaller.  Of  two  pictures  hung  on  the  wall,  equally 
lighted,  and  not  essentially  different  in  coloring, 
character  of  subject,  etc.,  the  larger  will  get  the  at- 
tention first.  Of  two  touches,  two  tones,  two  pains, 
similar  statements  may  be  made.  Quality  may 
have  some  influence.  Red,  for  instance,  may  at- 
tract the  attention  more  than  blue.  Visual  sensa- 
tions usually  take  precedence  over  auditory,  and 
olfactory  over  both.  All  of  these  sensational  factors 
are  of  slight  importance  as  compared  with  the  others 
mentioned  below,  and  their  effects  may  be  due  to  the 
feeling  factors  which  accompany  them. 

B.  Affective  Factors. — In  the  case  of  feelings, 
intensity  is  more  important  than  in  the  case  of  sen- 
sations. The  more  intense  feelings  always  have 
a  great  advantage  in  vividness.     Perceptions  and 


THE    DEGREES   OF   CONSCIOUSNESS         299 

ideas  attended  by  intense  feeling  are  therefore  usu- 
ally found  to  be  occupying  the  focus  to  the  exclu- 
sion of  complexes  with  weaker  feeling-components, 
in  accordance  with  the  association  factors  mentioned 
below.  Whether  one  sort  of  feeling  is  more  ef- 
fective than  another  in  this  way,  we  have  no  grounds 
for  affirming  or  denying,  since  it  is  not  possible  to 
equate  intensities  of  two  sorts  of  feeling.  We  can 
decide  that  the  pleasant  feeling  of  one  complex  is 
approximately  the  same  in  intensity  as  the  pleasant 
feeling  of  another,  or  at  least  not  appreciably  dif- 
ferent, but  comparison  of  pleasant  feeling  with  un- 
pleasant feeling  in  degree  of  intensity  is  definite  only 
when  one  is  noticed  to  be  relatively  much  greater 
than  the  other. 

C.  Association  Factors. — The  whole  matter  of 
the  rise  of  ideas  through  association  is  one  of  vivid- 
ness. One  percept  or  idea  occupying  the  focus  of 
consciousness  tends  to  bring  in  its  associates.  If 
the  primarily  focal  content  forms  with  its  associates 
what  we  call  a  single  object,  the  associates  are  sim- 
ply added  to  the  focal  content.  If  the  associates, 
on  the  other  hand,  form  objects  distinct  from  the 
primary  content,  the  latter  drops  out  as  one  of  the 
former  comes  in.  The  feelings  associated  with  a 
certain  percept  or  idea  come  under  the  first  rule, 


300  A    SYSTEM   OF   PSYCHOLOGY 

hence  the  tendency  above  noted,  for  the  content 
having  the  more  intense  feeling  associated  with  it  to 
gain  the  ascendency  over  the  content  with  less  in- 
tense feeling  associates.  The  statement  that  two 
distinct  objects  are  attended  to  successively  applies 
only  to  the  case  where  one  of  them  occupies  the 
focus  before  the  other  is  called  up  through  associa- 
tion. That  two  different  objects  may  occupy  the 
focus  simultaneously  under  certain  circumstances 
is  perhaps  true,  but  is  to  be  considered  later.  It 
must  be  noted,  however,  that  when  several  distin- 
guishable objects  form  a  functionally  connected 
group,  as  a  hunter  and  his  prey,  a  church  and  the 
congregation,  they  may  constitute  at  a  given  time  a 
single  co-ordinated  content,  although  from  other 
points  of  view  they  may  constitute  distinct,  even 
conflicting,  contents. 

D.  Relational  Factors. — Relations  determine  viv- 
idness of  related  content,  inasmuch  as  they  form 
nexus  among  the  factors  of  content.  Nothing  need 
here  be  added  to  the  discussion  of  the  function  of 
relations  in  association.  On  the  other  hand,  re- 
lations seem  to  have  a  distinct  advantage  in  vivid- 
ness over  sensorial  content.  In  a  focal  content  the 
relations  are  usually  the  most  vivid  part.  This  is 
especially  true  of  "  thought."     Our  thinking  eon- 


THE    DEGREES   OF  CONSCIOUSNESS         301 

stantly  tends  to  be  conceptual,  rather  than  of  the 
sensory-imaginative  type.  In  actual  perception  the 
situation  is  often  reversed,  and  the  sensational  fac- 
tors are  focal  at  the  expense  of  the  relational. 

E.  Other  Factors. — Anything  singled  out,  or  spe- 
cifically characterized  objectively,  is  thus  made  lia- 
ble to  especial  vividness.  The  first  and  last  letters 
of  a  written  word,  a  note  or  word  marked  by  a  pre- 
ceding or  succeeding  pause,  a  trilled  or  syncopated 
note,  a  bit  of  color  in  the  scenery  unlike  the  sur- 
rounding hues,  an  element  having  a  humorous  sig- 
nificance or  any  other  emotional  coloring  widely 
different  from  that  of  other  elements — these  receive 
especial  attention.     The  list  is  indefinitely  long. 

4.  Attention  and  Interest 

Interest  is  sometimes  named  among  the  condi- 
tions of  attention.  That  the  feeling  we  have  earlier 
referred  to  by  the  name  of  interest  does  predispose 
to  vividness  the  content  associated  with  it,  is  indis- 
putable. The  same  is  true  of  any  emotion  or  emo- 
tional factor. 

When,  as  is  sometimes  the  case,  attention  is 
treated  as  exclusively  a  matter  of  interest,  the  term 
interest  is  not  used  to  designate  an  affective  con- 
tent, but  an  abstract  potentiality.     Interest  ascribed 


302  A   SYSTEM  OF  PSYCHOLOGY 

to  any  possible  object  means  in  this  case  the  fact 
that  when  that  content  arises  it  will  probably  be 
vivid  (i.  e.,  attended  to),  and  that  the  probability 
of  the  rise  of  that  content  is  relatively  high.  Inter- 
est is  in  this  sense  by  no  means  a  cause  of  attention, 
but  a  mere  abstraction  from  the  observed  or  proba- 
ble course  of  attention-changes. 

It  is  so  easy  to  shade  from  one  meaning  of  the 
term  interest  to  another,  that  the  student  must  be 
on  the  alert  when  following  any  exposition  of  the 
psychology  of  attention  in  which  the  term  is  given 
an  important  place,  lest  he  be  led  to  accept  as 
analysis  what  is  merely  a  confusion  of  thought. 

5.  Vividness  and  Practical  Advantage 

The  greater  efficiency  of  conceptual  thought  as 
compared  with  thought  which  depends  more  largely 
on  the  sensory  image  can  hardly  be  disputed.  By 
efficiency  we  mean  here  the  celerity  and  accuracy 
with  which  a  conscious  result  is  obtained,  as  in 
solving  a  problem,  or  making  a  decision.  Hence, 
the  tendency  to  greater  vividness  of  relations  as  com- 
pared with  "imaged"  sensations  can  be  regarded 
as  having  arisen  or  having  been  conserved  because 
practically  advantageous.  The  same  interpreta- 
tion can  be  brought  to  bear  on  every  general  con- 


THE    DEGREES   OF   CONSCIOUSNESS  303 

dition  of  vividness.  The  objects  which  are  most 
intense  and  most  strongly  charged  with  feeling  are 
the  ones  to  which  it  is,  in  general,  mentally  advan- 
tageous to  attend. 

6.  Judgment 

The  distinction  between  concept  and  judgment 
is  entirely  a  matter  of  relative  vividness  among  the 
factors  of  these  complexes.  If  I  have  the  concept 
of  a  horse,  with  a  definite  relation  of  horse  to  hay 
especially  vivid,  I  have  (psychologically)  a  judg- 
ment which  I  express  (logically)  by  saying  that  the 
horse  eats  hay. 

In  general,  a  judgment  involves  two  concepts; 
but  again,  in  general,  no  concept  stands  alone.  I 
cannot  conceive  a  horse  without  several  other  sub- 
sidiary concepts  entering  into  the  content,  and,  in 
the  judgment,  one  of  the  subsidiary  concepts,  with 
a  definite  system  of  relations  linking  it  to  the  central 
concept,  simply  becomes  more  vivid. 

From  the  preceding  it  ought  to  be  plain  that  the 
function  of  the  judgment  is  the  growth  of  the  con- 
cept. If  the  relation  emphasized  by  the  judgment 
is  already  a  part  of  the  concept,  the  judgment  is 
analytic.  For  me  to  form  the  judgment  which  I 
express  logically  by  the  proposition,  "Water  lays 


304  A    SYSTEM   OP"   PSYCHOLOGY 

dust,"  adds  nothing  of  value  to  my  mental  content 
or  functions.  My  concept  of  water  already  in- 
cludes the  relations  to  desiccated  substances,  which 
I  call  wetness.  But  when  I  first  discovered  that 
water  can  be  produced  by  the  union  of  two  gases, 
the  judgment  constituted  by  my  apprehension  of 
that  (to  me)  new  relation  of  water  was  synthetic.  It 
permanently  modified  the  concept.  Included  in 
my  concept  of  water  from  that  time  forth  was  that 
relational  complex  which  I  express  when  I  say, 
"Water  is  composed  of  oxygen  and  hydrogen." 

7.  The  Scope  of  Attention 

How  many  things — how  many  functionally  dis- 
tinct factors  in  content — may  be  attended  to  at 
once?  In  general,  only  one,  as  you  may  verify 
introspectively  by  the  aid  of  a  little  experimenta- 
tion. Arrange  several  articles  on  a  table  in  front  of 
you,  and  if  a  clock  is  ticking,  or  a  gas  flame  audi- 
bly roaring  in  the  room,  and  if  the  finger  is  pressed 
firmly  on  some  hard  object — e.  g.,  the  edge  of  a 
paper-cutter — you  will  have  a  sufficient  range  of 
objects.  Attend  to  one  of  the  content  factors,  and 
the  others  coincidently  recede  from  the  focus  of 
consciousness.  Seldom,  if  ever,  can  you  succeed 
in  retaining  two  of  the  objects  at  high  vividness. 


THE   DEGREES   OF  CONSCIOUSNESS         o05 

When  an  object — an  ink-bottle,  for  instance — 
is  low  in  vividness  it  may  be  rather  uniformly  vivid. 
But  when  the  focus  of  attention  shifts  to  the  object 
it  is  apt  to  fall  upon  some  limited  feature.  Thus, 
when  attending  to  the  ink-bottle,  you  will  find  that 
it  is  the  top,  or  the  bottom,  or  the  cork,  or  the  label, 
or  the  ink,  or  some  such  detail  which  is  focal.  The 
other  portions  of  the  bottle  are  less  vivid.  We  may 
say  in  general  that  the  content  occupying  the  focus 
of  attention  is  relatively  simple.  But,  in  a  content 
which  does  at  one  time  occupy  the  focus,  we  may 
later  (in  memory)  discover  many  details.  These 
details,  in  the  later  analysis,  occupy  the  focus  suc- 
cessively. 

Several  relations  can  be  focal  simultaneously  only 
in  so  far  as  they  join  in  a  single  concept.  Two  dis- 
tinct concepts  are  probably  never  present  at  once, 
even  in  the  formation  of  a  judgment. 


CHAPTER   XVIII 

THE   TIME   RELATIONS  OF  CONSCIOUSNESS 
i.  Presentation  and  Image 

In  earlier  chapters  we  have  concluded  that  what 
is  commonly  known  as  the  image  is  not  different  in 
kind  from  sensation,  but  that  the  difference  is  in  the 
way  of  being  conscious.  The  difference,  in  short, 
is  in  the  time  factor.  If  we  are  now  conscious  of 
what  is  now  here,  the  content  is  called  sensation; 
if  we  are  now  conscious  of  what  was  formerly  here, 
the  content  is  called  image.  The  time  factor  needs 
somewhat  further  elaboration. 

There  are  two  distinct  temporal  phases  of  a  pres- 
entation, which  may  be  provisionally  distinguished 
by  reference  to  the  assumed  cortical  process.  The 
presentation  does  not  cease  when  the  cerebral  proc- 
ess ceases.  We  may  call  the  phase  of  sensation  in 
which  the  cortical  process  is  active  the  primary 
phase,  and  the  phase  after  the  practical  cessation 
of  the  cortical  process  the  secondary  phase.  This 
secondary  phase  of  the  presentation  is  distinct  from 

the  image. 

306 


THE   TIME   RELATIONS   OF  CONSCIOUSNESS     307 

If  we  observe  a  regular  series  of  brief  visual  or 
auditory  sensations — clicks  of  a  telegraph  sounder, 
or  flashes  of  light — we  find  that  they  may  be  so  ar- 
ranged that  the  successive  sensations  do  not  fuse; 
each  is  separate  and  distinct  from  the  preceding 
and  succeeding  ones;  but  several  may  be  simul- 
taneously present  to  consciousness.  If  four  suc- 
cessive sounds,  for  example,  are  given  in  one  sec- 
ond, they  may  be  apprehended  simultaneously, 
although  not  as  simultaneous.  You  may  easily 
demonstrate  this,  employing  taps  of  your  finger  or 
pencil  on  the  table.  When  the  fourth  tap  is  in  its 
primary  phase,  the  preceding  three  must  be  in  their 
secondary  phases.  If  they  were  yet  in  the  primary 
phase,  the  four  would  fuse  into  one  continuous 
sound.  Compare  the  four  just  when  the  fourth 
arises  with  the  same  four  a  few  moments  later  (as 
memory  images),  and  you  note  the  difference  at 
once.  As  apprehended  simultaneously,  they  are 
sensations  and  not  images. 

This  peculiarity  of  sensations  is  of  great  impor- 
tance in  practical  life — as,  for  example,  in  "taking" 
telegraphic  messages,  where  the  operator  is  con- 
scious of  a  sequence  of  dots  and  dashes  as  a  whole, 
instead  of  having  to  carry  the  first  part  of  a  letter 
in  memory  until  the  last  arrives.     In  spoken  and 


308  A    SYSTEM   OF   PSYCHOLOGY 

written  language,  too,  this  power  of  consciousness 
is  of  enormous  importance.  If  you  were  listening 
to  the  preceding  sentence  you  would  not  have  to 
understand  "enormous"  and  carry  it  over  in 
memory  to  modify  "importance";  you  would 
grasp  the  two  literally  together  with  a  vast  saving  of 
mental  process.  In  addition  to  the  practical  con- 
sequences of  the  secondary  phase  of  sensation  we 
find  an  important  aesthetic  factor  in  rhythm,  which 
is  made  possible  by  it,  and  to  the  discussion  of 
which  we  shall  proceed  in  a  moment. 

This  apprehension,  simultaneously,  of  factors 
which  are  apprehended  as  non-simultaneous,  is 
described  by  the  term,  "the  specious  present." 
The  present  moment,  referred  to  content  alone, 
stands  as  a  mere  inextended  point  dividing  the 
past  from  the  future.  Since  mathematics  and  logic 
must  regard  time  altogether  from  the  point  of  view 
of  content,  we  have  come  to  regard  this  as  the  real 
present.  Hence,  the  term  "specious  present" 
(apparent  or  seeming  present)  applied  to  the  pres- 
ent of  consciousness.1     But  this  "specious"   pres- 


1  This  explanation  of  the  term  "specious"  as  applied  to  the 
present  is  in  strict  accordance  with  the  intention  of  Mr.  E.  R. 
Clay,  who  first  used  the  term.  Cf.  James,  Principles  of  Psy- 
chology, vol.  I,  pp.  606  ff.  Other  explanations  (as  that  of  the 
Century  Dictionary)  are  obviously  erroneous. 


THE    TIME    RELATIONS   OF   CONSCIOUSNESS     309 

ent  is  just  as  "real"  as  the  other,  and  there  is  ab- 
solutely no  confusion  between  the  two  presents. 
Because  I  apprehend  the  successive  terms  A,  B,  C, 
D  simultaneously,  I  do  not  necessarily  apprehend 
them  as  simultaneous. 

2.  Rhythm 

A  fairly  regular  sequence  of  stimulations — clicks, 
taps  on  the  skin,  flashes  of  light,  etc. — does  not 
usually  give  rise  to  a  uniformly  progressing  series 
of  sensations.  The  greater  part  of  our  sensations 
belong  in  definite  groups,  as  in  the  case  of  words  of 
language,  and  the  grouping  habit  is  so  thoroughly 
ingrained  in  us  that  we  group  objects  which  have  no 
intrinsic  demands  for  such  treatment. 

Suppose  we  allow  water  to  drip  slowly  from  a 
small  tank  onto  a  tin  plate,  producing  thus  a  dis- 
tinct noise  for  each  drop.  Let  the  rate  of  flow — 
i.  c,  the  rapidity  of  the  succession  of  drops,  be  con- 
trollable. Suppose  at  first  we  choose  a  rate  of 
between  two  and  four  drops  a  second.  In  listening 
to  the  perfectly  uniform  series  of  sounds  thus  pro- 
duced, you  will  find  that  very  seldom  does  it  pro- 
ceed monotonously.  In  most  cases  the  sounds  are 
automatically  grouped  in  twos,  threes,  fours,  or  sixes. 
The  exact  numerical  size  of  the  group  will  depend 


310  A   SYSTEM   OF   PSYCHOLOGY 

on  the  rate,  the  intensity,  the  listener,  and  on  sug- 
gestions he  may  get  from  other  processes  he  is  ex- 
periencing or  has  experienced;  as  the  "clickety- 
click"  of  the  street-car  which  passed  the  building 
a  moment  or  two  before. 

The  listener  can  easily  give  himself  suggestions 
as  to  the  grouping.  If  he  thinks  of  hearing  a 
"three-group"  the  drops  will  usually  organize 
themselves  in  that  form.  The  chief  limitation  is 
that  the  groups  will  in  general  not  extend  over  two 
or  three  seconds,  although  occasionally  larger 
groups  are  formed.  This  temporal  limit  seems  to 
be  the  span  of  consciousness,  or  the  limit  of  the 
"specious  present."  Another  limitation  is  in  the 
number  of  the  sensations;  too  many  in  a  specious 
present  give  rise  to  confusion  and  abolish  regular 
grouping. 

If  the  terms  of  the  series  are  absolutely  uniform 
in  the  case  of  the  water-drops,  and  if  the  degree  of 
attention  is  fairly  constant,  the  grouping  depends 
altogether  on  the  time  relations  of  secondary  phases 
of  the  sensations.  When  the  final  term  of  a  group 
arises  the  foregoing  terms  of  that  group  are  still 
present;  with  the  arrival  of  the  first  term  of  the 
next  group  the  group  just  completed  disappear  from 
consciousness  as  presentations — the  slate  is  washed, 


THE   TIME    RELATIONS   OF   CONSCIOUSNESS     311 

as  it  were.  This  sort  of  a  rhythm  is  apparently  due 
to  the  periodic  contraction  of  the  specious  present, 
occurring  at  the  beginning  of  each  group. 

In  many  cases  attention  is  not  uniform.  The 
drops  may  be  heard  in  groups  of  four,  for  example, 
and  the  vividness  of  the  first  drop  may  be  higher 
than  that  of  the  succeeding  three.  This  is  "sub- 
jective accent"  properly  so  called. 

The  rhythm  is  much  more  distinctly  and  readily 
developed  if  "objective  accent"  is  permitted.  If, 
for  example,  by  holding  the  finger  on  the  tin  plate 
on  which  the  drop  falls  during  the  time  of  three 
drops,  and  lifting  it  for  the  fourth,  the  intensity 
of  the  fourth  drop  is  made  relatively  higher  than 
that  of  the  others,  the  drops  will  tend  to  fall  into 
groups  of  fours,  the  accented  drop  usually  being 
the  first  of  each  four.  Various  devices  are  em- 
ployed for  producing  series  of  auditory,  visual,  and 
tactual  sensations,  and  if  these  devices  are  so  ma- 
nipulated that  periodic  variations  in  intensity,  ex- 
tensity,  duration,  quality,  or  local  sign  are  intro- 
duced, these  variations  serve  as  accents  to  determine 
the  grouping.  Periodic  variations  of  the  time  rela- 
tion of  the  stimuli  may  also  produce  the  same  effect. 

With  objective  accent  the  periodic  shrinking  of 
the  specious  present  takes  place  just  as  when  there 


312  A    SYSTEM   OF   PSYCHOLOGY 

is  no  objective  accent;  and  the  groups  are  usu- 
ally eliminated  as  wholes.  If  the  groups  are  very 
short  two  or  even  three  groups  may  be  elimi- 
nated simultaneously,  the  contraction  of  the  spe- 
cious present  taking  place  with  every  second  or 
third  group. 

An  important  source  of  objective  accent  is  found 
in  muscular  sensation.  Very  often,  when  there 
seems  to  be  a  purely  subjective  accent,  it  will  be 
found  that  the  stimulations  are  accompanied  by 
slight  muscular  contractions  in  ringer,  arm,  throat, 
chest,  or  elsewhere,  and  these  are  accented  by  varia- 
tions in  intensity,  so  that  the  grouping  of  the  ex- 
ternally presented  sensation  is  really  directed  by  the 
accenting  of  the  muscular  sensations.  It  is  pos- 
sible that  pure  subjective  grouping  is  a  very  rare 
occurrence. 

Rhythm  is  important  in  music  and  in  poetry, 
especially  in  the  former;  the  span  of  consciousness 
demanded  by  the  rhythmic  groups  has  a  large  share 
in  the  determining  of  the  emotional  character  of 
the  composition.  A  short  musical  unit  tends  to 
light,  vivacious,  or  joyful  effects,  irrespective  of  the 
rapidity  of  succession  of  notes,  or  of  the  melodic 
intervals  employed.  A  unit  which  "draws  out" 
the   specious   present   slightly   beyond    the   normal 


THE    TIME    RELATIONS   OF   CONSCIOUSNESS     313 

length  produces  a  sombre  effect.  A  still  longer  unit, 
which  Is  divided  between  two  not  long  spans  of 
consciousness,  gives  an  effect  which  is  solemn,  but 
not  sad.  Specific  effects  are  produced  by  units  of 
such  length  that  two  occupy  a  long  span  or  a  short 
span.  All  these  effects  are  modified — sometimes 
counteracted — by  the  other  musical  factors  intro- 
duced by  the  composer.  In  music  of  the  so-called 
"intellectual"  sort  there  is  no  regular  relation  be- 
tween the  musical  unit  and  the  span  of  conscious- 
ness; the  unity  here  is  intentionally  ideational 
and  does  not  appeal  to  the  average  hearer,  who  is 
baffled  in  his  natural  attempts  to  fit  musical  unit  to 
specious  present,  and  only  by  repeated  experience 
acquires  the  other  method  of  appreciation. 

3.  Duration  of  Attention   to   Continuously  Presented 

Sensation 

The  rhythmic  variation  of  the  span  of  conscious- 
ness which  we  have  just  discussed  has  to  do  only 
with  sensations  of  an  intermittent  nature.  We  must 
now  consider  cases  where  the  stimulus  is  continu- 
ous and,  hence,  the  sensation  is  continuously  pre- 
sented. Such  a  case  is  afforded  by  the  note  of  a 
steadily  vibrating  tuning-fork,  or  the  noise  of  a  small 
stream  of  water. 


314  A   SYSTEM   OF   PSYCHOLOGY 

In  most  cases  these  continuous  noises,  if  rather 
loud,  persist  in  the  focus  of  consciousness  for  some 
time;  perhaps  for  minutes,  perhaps  for  hours. 
After  awhile,  however,  the  sound  may  become  mar- 
ginal. The  duration  of  a  continuously  presented 
sensation  or  sensational  complex  in  focal  conscious- 
ness depends  on  the  rise  of  other  sensations  or 
ideas  which  may  take  its  place.  If  you  sit  beside 
a  water-fall  with  your  mind  at  rest,  the  purl  of  the 
water  may  continue  vivid  for  hours,  or  if  temporar- 
ily obscured  by  the  other  presentations  of  nature  or 
by  fleeting  ideas,  returns  quickly  to  its  place.  But, 
if  you  have  a  problem  to  solve,  a  book  to  read,  a 
friend  to  talk  with,  or  a  hill-side  to  watch  for  game, 
the  water-fall  quickly  becomes  an  inconspicuous  fac- 
tor in  the  total  field  of  consciousness.  So  it  is  with 
all  other  presentations.  The  intense  stimulus  may 
force  the  sensation  into  the  focus  for  awhile,  but 
finally  the  mere  intensity  becomes  ineffective. 

The  effect  of  habituation  in  eliminating  the  per- 
sistent sensation  from  attentive  consciousness  may 
be  illustrated  in  a  great  many  ways.  The  noise 
of  the  street  which  annoys  the  countryman  stay- 
ing at  your  house  is  practically  unnoticed  by  you; 
yet  the  ear  does  not  lose  its  sensitiveness  to  the  noise 
as  does  the  nose  to  a  continuing  odor.     During  the 


THE   TIME    RELATIONS   OF   CONSCIOUSNESS     315 

greater  part  of  the  day  you  hardly  notice  the  sensa- 
tions aroused  by  the  rubbing  of  your  clothing  on 
your  skin;  to  a  savage  first  clothed  the  sensations 
are  intolerable.  The  lights  of  the  lamps  and  win- 
dows on  the  street  at  night  you  scarcely  notice  at 
all;  your  rural  friend  is  so  attentive  to  them  that  he 
can  hardly  converse  with  you.  We  find,  in  general, 
in  addition  to  the  physiological  adaptation  which 
protects  us  from  continued  stimulation,  a  sort  of 
protective  adaptation  of  consciousness  itself  by 
which  the  persistent  sensations  not  eliminated  by 
physiological  adaptation  are  relegated  to  the  mar- 
ginal consciousness,  unless  they  exercise  solicitations 
other  than  those  of  mere  intensity. 

The  relegation  of  intense  sensations  to  marginal 
consciousness  through  habituation  is  realized  also 
in  case  of  sensations  not  continuous,  but  which 
are  repeated  at  frequent  intervals.  The  train  rush- 
ing by  every  half-hour;  the  clock  striking  every 
hour;  even  a  church-bell  ringing  at  morning,  noon, 
and  night;  soon  becomes  without  power  to  disturb 
the  focus.  If  the  interval  between  stimulations  is 
long  this  habituation  does  not  occur.  Thus,  a 
church-bell  ringing  only  on  Sunday  mornings  may 
be  as  vivid  at  the  end  of  a  year's  disturbance  thereby 
as  at  the  beginning. 


316  A   SYSTEM   OF   PSYCHOLOGY 

4.  The  Fluctuations  of  Minimal  Sensations 
Sensations  of  uniform  minimal  intensity  show  a 
peculiar  intermittence  in  presentation,  to  which  is 
commonly  applied  the  confusing  name  "fluctua- 
tions of  attention."  If  one  attempts  to  listen  to  a 
sound,  for  instance,  which  is  physically  constant 
and  just  above  the  threshold,  he  finds  that  the  sound 
is  clearly  discernible  for  short  periods  and  in  inter- 
vening periods  is  not  to  be  heard  at  all.  The  times 
of  absence  and  presence  may  vary  from  a  fraction 
of  a  second  to  over  ten  seconds.  Faint  sensations 
of  certain  other  modes  behave  in  the  same  way.  A 
small  gray  spot  on  a  background  slightly  darker, 
for  example,  will  appear  and  disappear  periodically 
under  the  best  obtainable  conditions  of  attention  and 
accommodation. 

It  has  been  supposed  that  these  fluctuations  are 
due  to  varying  states  of  muscular  adjustment  in  the 
end-organs,  and,  in  fact,  slight  changes  in  accom- 
modation have  been  found  to  accompany  the  visual 
fluctuations.  This  theory  is  excluded  by  experi- 
ments which  absolutely  preclude  any  adjustmental 
variation  and  which  yet  find  fluctuations  occurring. 
The  theory  which  is  most  probable  assumes  the 
physiological  cause  to  be  a  periodic  variation  in  the 


THE   TIME    RELATIONS   OF   CONSCIOUSNESS     317 

functioning  of  the  nervous  mechanism;  either  of 
the  nerve  terminals  of  the  end-organ  or  of  the  cor- 
tical cells.  The  variation,  if  it  occurs,  is  very  slight, 
for  no  periodic  increase  or  decrease  in  intensity  of  a 
sensation  from  a  physically  constant  stimulus  con- 
tinuously above  the  threshold  is  discernible.1 

The  phenomena  in  question  are  therefore  not 
"fluctuations  of  attention"  in  a  sense  in  which  that 
expression  would  naturally  be  taken.  If  the  at- 
tention does  actually  shift  from  a  sensation  under 
observation,  the  disappearance  of  the  sensation  can- 
not be  noted  unless  the  disappearance  comes  be- 
fore the  shift  or  after  the  attention  returns.  Yet 
the  fluctuations  are,  in  another  sense,  those  of 
"attention,"  for  the  essential  condition  of  the  ex- 
periment is  that  the  attention  shall  be  to  the  image 
of  the  presentation  in  the  intervals  when  the  sen- 
sation is  not  intuited. 

The  difficulty  of  distinguishing  between  the  sen- 
sation and  the  image  in  the  case  where  the  stimula- 
tion is  minimal  enormously  complicates  observa- 
tion. In  certain  cases  the  observer  is  unable  to 
distinguish  at  all,  as  is  shown  by  his  continuing 
to  report  the  sensation  long  after  the  stimulus  has 
been  suspended  completely  but  gradually.  In  such 
1  This  is  true  for  auditory  sensations,  at  least. 


318  A   SYSTEM   OF   PSYCHOLOGY 

cases  the  characteristic  fluctuation  cannot  be  ob- 
tained; the  sensation  seems  either  present  all  the 
time  or  absent  all  the  time. 

5.  The  Selective  Fluctuations  of  Vividness 

When  several  complexes  are  presented  they  are 
apt  to  occupy  the  focus  alternately.  As  I  gaze  at 
the  desk  before  me  my  attention  is  centred  now  on 
the  ink-bottle,  now  on  the  pile  of  books,  now  on  the 
ink-bottle  again,  now  on  the  drop-light,  now  on  the 
stack  of  letters.  Even  when  I  attempt  to  attend 
continuously  to  the  ink-bottle  I  find  that  I  am  at- 
tending to  it  only  for  short  periods,  the  focus  being 
occupied  by  various  other  things  in  the  intervals. 
Not  visual  presentations  alone  jostle  the  presenta- 
tion of  the  ink-bottle.  Auditory,  tactual,  olfactory, 
and  organic  presentations  take  their  turn.  Ideas 
also  flip  in  and  out  to  the  detriment  of  my  study 
of  the  ink-receptacle. 

This  periodicity  of  focal  consciousness  is  one  of 
its  most  uniform  characteristics.  In  general,  we 
can  attend  to  anything  only  by  a  succession  of  short 
periods.  This  holds  for  ideas,  of  course.  Try  to 
think  of  any  one  thing  and  see  how  intermittently 
you  succeed. 

Many  striking  illustrations  of  the  selective  flue- 


THE   TIME    RELATIONS   OF   CONSCIOUSNESS     319 

tuations  of  attention  are  easily  available.  Retinal 
rivalry  is  one  sueh.  Place  in  a  stereoscope  two  sim- 
ple pictures  which  are  radically  different;  a  num- 
ber of  concentric  circles  in  one,  and  a  number  of 
parallel  lines  in  the  other;  or  two  large  letters,  or 
two  fields  of  different  colors.  On  looking  through 
the  stereoscope  in  the  usual  way — one  eye  seeing 
each  card — it  will  be  found  that  the  two  figures  or 
two  colors  are  seen  alternately.  Sometimes  both 
of  two  colors  will  be  seen,  but  in  different  parts  of 
the  field,  or  parts  of  both  diagrams  will  be  seen 
simultaneously.1 

The  "stair-case  figure,"  "  tumbling  block  figure," 
and  other  illusions  of  "reversible  perspective"  are 
also  illustrations  of  fluctuations  of  attention.  These 
are  simple  figures  so  drawn  that  the  space  relations 
are  ambiguous.  Thus,  in  Figure  13,  the  skeleton 
chair  may  be  seen  either  facing  you  or  facing  away 


1  If  the  two  pictures  are  so  arranged  that  no  detail  of  one 
occupies  a  retinal  point  corresponding  to  a  point  of  the  other 
eye,  occupied  by  a  detail  of  the  other  picture,  the  two  may 
combine.  Thus,  if  a  figure  before  one  eye  has  an  open  space 
in  the  centre,  and  a  smaller  figure  be  presented  to  the  retinal 
area  of  the  other  eye  corresponding  to  this  space,  the  figures 
may  be  seen  combined.  Some  observers  report  binocular 
color  combinations;  red  presented  to  one  eye,  and  blue  to  the 
other,  giving  purple,  etc.  But  this  observation  may  for  the 
present  be  doubted.  Complementary  colors  will  give  gray, 
because  adaptation  to  the  two  takes  place  rapidly. 


320 


A   SYSTEM   IN   PSYCHOLOGY 


from  you.  After  seeing  it  both  ways  it  is  practically 
impossible  to  see  it  either  way  continuously.  At- 
tempts have  been  made  to  connect  these  changes 
with  eye-movements,  or  spatial  shifts  of  attention, 
i.  c,  from  one  point  of  the  figure  to  another.  At 
certain  times  the  chair  will  face  you  while  you  at- 


^ 

K 

/            V 

> 

/ 

= 

3 

TJ 

a 

c 

Fig.  13. 


tend  to  the  corner  at  a,  and  reverse  its  position  when 
your  attention  shifts  to  b.  This  is  as  if  the  point 
fixated  tends  to  become  the  near  point.  But  the 
same  shift  of  perspective  may  be  produced  with  the 
opposite  shift  of  attention;  all  depends  on  which 
habit  is  formed.  In  general,  any  such  objective  way 
of  determining  a  shift  of  the  perspective  operates 
through  association.  You  expect  to  see  the  figure 
in  a  certain  position  when  a  certain  change  is  made, 


THE    TIME    RELATIONS   OF   CONSCIOUSNESS     321 

or  you  have  uniformly  observed  it  in  a  certain  posi- 
tion with  a  certain  direction  of  attention.  Hence, 
the  result. 

The  percept  based  on  the  lines  of  the  reversible 
perspective  figure  is  largely  reproduced.  The  sim- 
ple lines  of  figure  13,  for  example,  are  associated 
with  other  features  of  chairs  in  both  positions  equally 
well.  We  have,  therefore,  a  selective  fluctuation  of 
the  two  reproduced  factors,  first,  one  uniting  with 
the  presented  content,  and  then  the  other  taking 
its  place.  The  exact  moment  of  the  transformation 
may  be  determined  by  such  factors  as  shift  of  eye 
in  any  direction,  provided  the  shift  has  become 
associated  with  that  particular  change. 

Figures  14  and  15  show  a  sort  of  fluctuation  akin 
to  that  of  the  reversible  perspective  figures.  After 
looking  carefully  at  a  and  b  (of  either  figure),  c 
alone  will  probably  be  seen  alternately  with  the 
aspect  of  a  and  h. 

Fluctuations  of  perception  based  on  ambiguous 
impressions  of  senses  other  than  visual  might  be 
produced.  These  ambiguous  impressions  are,  how- 
ever, not  so  simply  obtainable  in  the  other  sense- 
realms.  One  experiment  may  be  made  in  the  fol- 
lowing way:  Obtain  a  revolver  with  round  barrel 
and  a  bottle  having  a  neck  of  the  same  diameter 


322 


A   SYSTEM   OF  PSYCHOLOGY 


and  thickness  as  the  muzzle  of  the  revolver.  Press 
the  muzzle  of  the  revolver  and  the  mouth  of  the 
bottle  alternately  on  the  temple  of  the  subject  (first 


Fig.  15. 

removing  the  cylinder  of  the  revolver!),  allowing  the 
subject  to  see  the  object  each  time.  Then,  with 
the  subject's  eyes  closed,  press  either  one  against 
the  temple  and  in  -many  cases  he  will  perceive  the 
ring  of  pressure  and  temperature  sensations  alter- 
nately as  the  pistol  and  as  the  bottle. 


THE   TIME   RELATIONS  OF  CONSCIOUSNESS     32i> 

6.  The  Conditions  of  Constant  Attention 
Constant  attention  to  one  object  in  a  normal  con- 
dition means  one  of  two  things:  either  the  object 
is  intermittently  in  the  focus  or  else  the  object  in- 
volves several  discriminable  details  which  occupy 
the  focus  alternately  or  in  succession.  To  attend 
in  actual  continuity  to  a  bare  sound  or  color,  even 
to  one  of  considerable  intensity,  is  impossible. 
But  the  sensation  may  persistently  return  to  the 
focus  after  each  ousting,  and  the  results  be  prac- 
tically the  same  as  if  it  had  occupied  the  focus  con- 
tinuously. In  the  case  of  a  more  complex  object, 
as  the  ink-bottle  on  your  table,  you  find,  as  we  al- 
ready have  noted,  your  attention  shifting  from 
feature  to  feature. 

The  strongest  determinant  of  persisting  recur- 
rence is  emotional  coloring.  That  which  you  de- 
sire or  hate  or  love,  etc.,  dwells  long  (with  due  re- 
gard to  the  principle  of  intermittence)  in  the  focus 
of  attention.  The  naturalist  may  observe  for  hours 
a  certain  small  animal  because  he  has  a  strong 
emotional  interest  in  it  and  in  its  relation  to  certain 
other  animals.  His  attention  courses  rapidly  over 
a  great  many  details,  and  many  factors  related  to  it, 
but  comes  back  again  and  again  to  the  same  features. 


324  A   SYSTEM  OF   PSYCHOLOGY 

It  may  be  asked,  "  Why  does  not  the  boy  continue 
to  attend  to  his  Latin  lesson,  since  he  hates  it?" 
The  answer  is  that  he  really  does  not  hate  it:  it  has 
not  even  that  vital  emotional  interest  for  him.  It 
deadens  his  emotions  in  so  far  as  he  attends  to  it, 
and,  hence,  he  does  not  attend,  except  as  far  as  the 
fear  of  consequences  or  desire  of  reward,  or  pride, 
or  some  other  emotional  state  may  supply  the  neces- 
sary coloring.  Give  the  boy  something  he  hates — 
a  boy  rival,  a  hysterical  teacher — and  he  will  attend 
to  that  object  with  ease  and  persistence. 


CHAPTER  XIX 

THE  SUBCONSCIOUS 
I.  The  Lower  Limit  of  Vividness 

A  sensational  object  may  be  reduced  enor- 
mously in  vividness  by  the  change  which  we  describe 
as  passing  from  the  focus  into  median  conscious- 
ness, and  yet  the  intensity  of  the  sensation  be  little, 
if  any,  reduced.  This  fact  suggests  the  question 
how  far  this  reduction  of  vividness  may  be  carried. 
There  are  two  forms  of  this  question:  (1)  May  a 
sensation  of  zero  vividness  exist?  A  sensation  of 
zero  vividness  would  be  one  of  which  no  person  is 
conscious  at  all.  This  question  is  strictly  meta- 
physical, and  although  it  is  possibly  the  most 
fundamental  of  all  the  questions  concerning  con- 
sciousness, we  cannot  consider  it  here.  (2)  May 
a  sensation  be  so  reduced  in  vividness  that  analytic 
consciousness  of  it  is  impossible?  An  affirmative 
answer  to  this  question  would  involve  the  admission 
that  there  might  be  consciousness  of  the  given  sen- 
sation in  a  complex  of  which  it  is  a  part,  although 

the  sensation  is  not  capable  of  being  singled  out 

325 


326  A   SYSTEM   OF   PSYCHOLOGY 

therefrom.  There  can  be  no  doubt  us  to  the  ex- 
istence of  sensational  objects  in  this  condition,  and 
it  is  to  this  condition  that  the  term  "subconscious" 
is  properly  applied.  The  term  "subconscious"  has 
been  much  misused  of  late  by  quasi-psychologists 
and  by  physicians,  and  it  has  been  made  to  cover 
a  multitude  of  bizarre  and  absurd  theories;  hence, 
the  conception  of  a  psychological  subconsciousness 
needs  our  careful  consideration. 

2.  What  the  Subconscious  is  Not 

Popular  writers  tend  to  confuse  the  subconscious 
with  the  conditions  of  automatic  and  reflex  move- 
ments. Because  a  complex  action,  such  as  walk- 
ing or  knitting,  is  learned  through  consciousness 
of  the  details  of  the  action,  and  is  later  performed 
without  consciousness  of  these  details,  the  details, 
it  is  said,  have  been  turned  over  to  the  "subcon- 
scious." Of  course  this  is  true  if  by  subconscious- 
ness we  mean  simply  that  which  is  below  the  level 
of  consciousness,  and  certainly  these  details  are 
taken  care  of  by  physiological  mechanisms  which 
do  not  require  consciousness  to  direct  them.  The 
authors  to  whom  we  refer  really  mean  more  than 
this,  and  conceive  of  a  lower  level  of  consciousness 
attending  to  the  whole  mass  of  such  automatic  ac- 


THE   SUBCONSCIOUS  '■>-< 

tions.  There  have  not  been  lacking  enthusiasts 
who  have  considered  digestive  functions  and  the 
growing  of  the  nails  as  supervised  by  this  subsidiary 
consciousness. 

Another  misuse  of  the  concept  of  subconscious- 
ness is  to  consider  it  as  the  repository  of  forgotten 
ideas.  The  remarkable  fact  that  something  which 
has  not  returned  to  consciousness  for  a  long  time — 
some  incident  of  childhood,  for  example — may  at 
any  time  come  back,  has  led  the  wilder  theorizers 
to  suppose  that  all  content  is  contained  in  the 
"  mind"  in  very  much  the  same  form  in  which  it  was 
originally  in  consciousness.  The  normal  conscious- 
ness, they  say,  includes  but  a  small  part  of  the  total 
field.  The  vast  remainder  is  in  subconsciousness. 
Recollection  is,  accordingly,  only  the  movement  of 
an  idea  from  subconsciousness  into  consciousness. 
The  idea  existed  in  your  mind  during  the  interval 
when  it  was  forgotten. 

It  is  absolutely  necessary  for  the  student  to  rid 
himself  of  all  such  fantastical  notions.  Content 
forgotten  is  in  general  not  in  any  sort  of  conscious- 
ness, although  it  may  have  its  effects  in  present 
consciousness.  The  learning  of  motor-adjustments 
is  the  process  of  turning  those  adjustments  over  to 
mechanisms  which  need  no  conscious  supervision. 


32S  A   SYSTEM   OF   PSYCHOLOGY 

3.  The  Two  Sorts  of  Marginal  Consciousness 
As  I  sit  here  writing  I  do  not  consciously  hear  the 
ticking  of  the  clock.  Yet,  if  the  clock  should  stop 
I  would  be  aware  of  the  stopping.  I  may  be  so 
absorbed  in  my  task  that  if  the  clock  strikes  I  do 
not  notice  it  at  the  time.  But  several  minutes  later 
I  may  recall  the  striking  and  in  memory  count  the 
strokes. 

We  are  constantly  subjected  to  stimuli  of  all  sorts 
which  give  rise  to  sensations,  but  these  sensations 
do  not  rise  to  any  considerable  degree  of  vividness. 
In  the  vast  majority  of  cases  these  sensations  and 
sensation-complexes  cannot  be  recalled  or  remem- 
bered unless  unusual  means  are  employed.  Nor- 
mal recall,  as  we  have  explained,  depends  princi- 
pally on  association,  and  association  depends  on 
vividness.  Various  means  for  the  recall  of  what 
was  perceived  marginally  or  subconsciously  may 
be  employed.  For  example,  the  subject  may  be 
hypnotized,  and,  when  questioned  in  that  state,  may 
give  evidence  of  the  recall  of  percepts  which  he 
did  not  notice  at  all.  The  subconscious  percepts 
may  be  obtained,  in  the  first  place,  by  calling  his 
attention  strongly  to  some  visual  object  to  which 
he   turns   the  line  of  regard,   and  simultaneously 


THE   SUBCONSCIOUS  329 

displaying  some  object  in  peripheral  vision.  In 
the  hypnotic  state  the  subject  may  describe  the 
object  which  he  did  not  know  that  he  saw.  The 
theorists  have  explained  this  by  saying  that  by 
hypnosis  the  subconscious  part  of  the  mind  is  made 
conscious.  This  really  amounts  to  saying  that  we 
don't  know  as  yet  how  the  phenomena  are  pro- 
duced. The  recall  of  subconsciously  perceived  ob- 
jects may  occur  in  a  reverie  or  in  the  pathological 
state  of  "crystal  gazing."  In  the  latter  state  the 
subject,  thrown  into  a  state  of  light  hypnosis  by 
gazing  fixedly  into  a  crystal  sphere  or  a  bowl  of 
water  held  close  to  the  eyes,  obtains  visual  hallu- 
cinations in  which  former  percepts,  subconsciously 
perceived,  appear.  Another  aid  to  the  recall  of 
subconsciously  perceived  objects  consists  in  show- 
ing the  subject  a  part  of  the  former  object,  which 
may  recall  the  remainder  of  the  details,  since  asso- 
ciation of  a  certain  strength  is  established  even  at 
the  low  vividness  of  the  subconsciously  perceived 
object. 

In  none  of  these  cases  is  it  necessary  to  assume 
a  subdepartment  of  consciousness  in  which  the  per- 
cepts are  held  over  between  the  original  perception 
and  the  recall.  The  contents  are  perceived,  dis- 
appear, and  are  recalled  just  like  any  percepts,  ex- 


330  A   SYSTEM  OF   PSYCHOLOGY 

cept  for  the  fact  that  the  low  vividness  of  the  per- 
ception makes  recall  difficult. 

The  effect  of  the  subconscious  perception  may 
be  demonstrated,  even  when  recall  is  impossible. 
If  you  present  to  a  subject  a  number  of  cards  con- 
taining simple  marks  or  designs,  some  of  which  he 
has  previously  seen  subconsciously,  and  if  you  ask 
him  to  choose  several  from  the  number,  he  will  be 
apt  to  choose  the  ones  which  were  previously  seen. 
The  above  are  typical  experimental  procedures  for 
demonstrating  the  existence  of  subconscious  per- 
ception. 

The  second  sort  of  marginal  consciousness  is 
rather  hypothetical.  If  it  exists,  it  is  the  content 
produced  by  stimulation  which  is  so  low  in  intensity 
that  it  cannot  be  vivid  even  under  the  best  normal 
conditions.  A  sound,  for  instance,  may  be  so 
weak  physically  that  it  cannot  be  perceived,  al- 
though the  air-waves  are  actually  causing  nerve- 
excitation  in  the  ear.  This  is  shown  by  the  fact 
that  the  sudden  stoppage  of  a  very  weak  (physical) 
tone  may  be  clearly  perceived,  even  though  the  tone 
itself  may  have  been  imperceptible.  It  may  be 
said  that  the  tone  was  in  marginal  consciousness,  or 
subconsciousness,  and  this  view  is  supported  by 
the  introspection  of  the  persons  taking  part  in  such 


THE   SUBCONSCIOUS  331 

experiments.  What  is  heard  at  the  moment  of  the 
interruption  of  a  stimulus  is  described  as  the  cessa- 
tion of  a  tone,  and  not  simply  some  disturbance 
which  might  be  taken  to  mean  the  cutting  off  of 
the  stimulus.  The  interpretation  of  these  phenom- 
ena and  similar  phenomena  in  other  sense-realms 
is  beset  with  difficulties;  neither  the  arguments  for 
the  subconscious  explanation  nor  the  objections  to 
it  are  very  weighty.  Hence,  the  matter  is  best  re- 
garded as  a  problem  for  experimentation  rather 
than  for  theorizing. 

4.  Multiple  Personality 

The  strongest  impulse  to  postulate  a  subcon- 
sciousness of  the  sort  we  are  unwilling  to  admit 
comes  from  certain  phenomena  of  abnormal  psy- 
chology which  are  known  as  "  alternations  of  per- 
sonality"  or  "  multiple  personality."  In  some  cases 
a  patient  may  suddenly  forget  the  events  of  his  past 
life  and  lose  the  habits  and  traits  of  character 
which  previously  have  distinguished  him.  He  be- 
comes by  this  rapid  transformation  a  man  of  an 
entirely  different  sort;  he  may  call  himself  by  an- 
other name;  we  may  say  he  has  a  new  personality. 
The  patient  may  continue  for  months  in  his  new 
life,  and  then  suddenly  his  former  memories  may 


332  A   SYSTEM   OF   PSYCHOLOGY 

return,  and  with  their  return  the  memory  of  the 
intervening  months  be  lost.  He  returns  to  the  first 
personality  and  knows  nothing  of  the  second. 
After  a  longer  or  shorter  time  the  patient  may  re- 
lapse into  the  second  personality,  remember  now 
all  that  occurred  when  he  had  this  personality,  and 
forget  both  periods  of  the  first  The  two  person- 
alities may  continue  to  alternate,  or,  in  other  words, 
the  person  may  continue  to  alternate  between  the 
two  conditions.  There  may  be  three  or  more  dis- 
tinct personalities  involved  and  the  conditions  in 
regard  to  memory  may  be  much  more  complicated 
than  in  the  case  which  we  have  just  described.  The 
patient,  for  example,  when  he  has  personality  No.  1 
may  know  nothing  of  what  has  occurred  when  he 
had  either  of  the  other  personalities.  But  when  he 
has  personality  No.  3  he  may  remember  perfectly 
all  that  happened  while  he  was  in  the  other  two 
states.  He  may  insist  that  the  experiences  in  states 
1  and  2  were  not  his  experiences,  but  were  the  ex- 
periences of  some  other  person. 

If  we  conclude,  as  some  psychologists  have  done, 
that  the  different  abnormal  personalities  exist  simul- 
taneously, and  that  sometimes  one,  sometimes  an- 
other, gets  the  upper  hand,  forcing  the  experiences, 
memories,  and  processes  forming  the  others  out  of 


THE   SUBCONSCIOUS  333 

consciousness,  either  as  subconscious  or  co-con- 
scious states,  the  statement  of  the  case  from  the 
point  of  view  of  pathology  and  therapeutics  is 
simple.  The  personality  of  the  individual  appar- 
ently has  lost  its  organic  unity,  and  has  fallen 
into  two  or  more  fragments  which  are  loosely  con- 
nected with  each  other.  If  by  the  use  of  proper 
means  (as,  e.  cj.,  hypnosis)  the  fragments  of  the  per- 
sonality are  reunited,  the  patient  is  cured.  But 
the  hypothesis  of  co-consciousness  gives  us  no  real 
information  as  to  the  actual  significance  of  the 
patient's  symptoms,  nor  as  to  the  actual  processes 
involved  in  the  removal  of  the  symptoms. 

The  acceptance  of  the  subconscious  or  co-con- 
scious explanation  of  alternating  personality  would 
logically  involve  the  acceptance  of  the  same  expla- 
nation for  the  forgotten  ideas  of  normal  life.  On 
the  other  hand,  we  can  state  the  facts  of  the  aberra- 
tions of  memory  in  pathological  cases  without  in- 
volving the  hypothesis  of  the  unknown,  just  as 
easily  as  we  can  state  the  conditions  in  normal  cases. 
In  neither  the  pathological  nor  the  normal  cases  is 
it  necessary  to  assume  that  forgotten  ideas  are  car- 
ried along  in  a  co-consciousness  during  the  period 
in  which  they  are  not  remembered. 

As  for  the  non-ideational  factors  involved  in  per- 


334  A   SYSTEM   OF   PSYCHOLOGY 

sonality — habits  of  action  and  emotion — the  as- 
sumption of  a  co-consciousness  adds  nothing  to  the 
explanation  of  their  appearance  and  disappearance. 
To  say  that  a  man  has  a  certain  habit  of  speech,  for 
example,  means  simply  that,  as  a  matter  of  fact, 
his  vocal  organs  move  in  a  certain  way.  If  the 
vocal  organs  cease  to  function  in  the  way  indicated, 
and  function  in  a  different  manner,  the  habit  has 
become  non-existent.  It  cannot  coexist  with  the 
new  habit,  although  the  nervous  mechanism  may 
not  be  so  completely  modified  that  it  will  not  event- 
ually return  to  its  earlier  condition  and  reinstate 
the  old  habit. 

It  is  true  that  a  large  part  of  habit  is  ideational; 
the  bodily  functions  are  influenced  by  the  processes 
in  representative  consciousness.  But  an  emphasis 
on  this  aspect  of  habit  simply  brings  us  back  to 
the  first  problem:  how  to  account  for  the  ideas 
which  were  in  consciousness  and  may  be  in  con- 
sciousness again,  but  are  out  of  consciousness  at 
present. 

We  are  justified  in  concluding  that  the  assumption 
of  a  detached  subconsciousness  or  co-consciousness 
to  explain  the  phenomena  of  alternating  person- 
ality is  not  at  present  defensible,  since  the  idea- 
tional problems  involved  in  these  phenomena  are 


THE   SUBCONSCIOUS  335 


quite  like  those  involved  in  all  mental  life,  and  the 
problems  of  neural  disposition  and  modification  are 
not  affected  in  any  way  by  the  hypothesis  of  co- 
consciousness. 


CHAPTER  XX 

THE  EGO 

Experience  cannot  be  completely  accounted 
for  in  terms  of  bare  consciousness  and  the  content 
alone.  Experience  of  any  content  intrinsically 
implies  something  experiencing  that  content.  The 
immediate  fact  of  one's  own  consciousness  is  always 
something  which  may  be  expressed  by  the  words, 
"  I  perceive,"  "  I  feel,"  "  I  imagine,"  etc.  The  "  I," 
or  real  Ego,  which  is  the  essential  centre  of  reference 
for  the  whole  of  the  content  of  consciousness,  is  not 
itself  a  fact  of  content,  and  hence  is  not  a  feature  of 
psychological  analysis:  it  is  the  one  thing  which, 
as  the  subject,  stands  over  against  the  whole  of 
objectivity,  and  hence,  while  not  discovered  by  any 
analysis,  it  is  involved,  not  only  in  every  attempt  at 
analysis,  but  in  every  bit  of  experience. 

The  celebrated  formula  of  Descartes,  Je  peruse, 
done  je  suis,  expresses  what  is  immediately  given 
as  a  fact  of  experience.  Thinking,  in  the  Cartesian 
terminology,  is  exactly  synonymous  with  being  con- 
scious in  ours.  What  Descartes  says  is  that  con- 
sciousness  is   intrinsically   something   which   con- 

336 


THE   EGO  337 

cerns  an  "I"  or  "Ego":  that  there  is  no  such  thing 
as  impersonal  experience.  So  far  we  must  agree 
with  Descartes;  but  he  follows  this  statement  of 
inevitable  introspection  with  the  assumption  that 
the  "I"  is  a  thinking  substance,  and  in  this  step  we 
cannot  follow. 

The  "I"  is  not  anything  which  can  be  defined 
in  terms  of  objectivity — as  the  metaphysical  sub- 
stance is  necessarily  defined.  It  is  the  pure  subject, 
which  is  uniquely  and  antithetically  removed  from 
all  objectivity,  and  which  is  yet  involved  in  all  ref- 
erence to  objectivity. 

Any  attempt  at  the  discussion  of  the  "I"  involves 
us  in  a  maze  of  paradoxes.  The  "I"  cannot  be 
discussed,  because  it  is  actually  non-objective.  It 
has  no  qualities:  and  yet  this  very  statement  is  a 
quasi-qualitative  ascription.  The  only  unambigu- 
ous statement  we  can  make  concerning  it  is  that  "I 
experience"  or  "I  am  conscious." 

There  is  a  method  of  explaining  away  the  "I" 
sometimes  adopted  by  psychologists,  which  consists 
in  assuming  that  content  experiences  itself.  Thus, 
one  "state  of  consciousness"  (using  this  term  as 
synonymous  with  the  term  "content")  is  assumed 
to  experience  the  state  which  just  precedes  it  in 
time:    or,  one  group  of  content  factors  is  assumed 


.338  A   SYSTEM   OF   PSYCHOLOGY 

to  experience  the  remainder  of  the  factors  in  any 
given  content.  The  subject,  in  accordance  with 
this  theory,  is  identified  with  one  portion  of  the 
content,  and  the  other  portions  of  content  are  de- 
scribed as  the  apprehended  objects.  There  are 
several  other  forms  of  the  content-subject  hypoth- 
esis. One  form  of  the  hypothesis  does  not  sup- 
pose a  definite  part  of  the  content  functioning  at  a 
given  time  as  the  subject,  but  simply  assumes  in  a 
more  vague  way  that  the  varying  details  of  the  con- 
tent which  is  present  at  a  given  moment  are  present 
by  virtue  of  being  in  a  definite  sort  of  mutual  re- 
lationship. This  relationship  constitutes  at  once 
the  consciousness  and  subjectivity:  it  is  subjectivity 
without  a  subject. 

These  views  assume  at  once  more  and  less  than 
experience  gives  us.  They  assume,  in  the  first  place, 
a  relationship  in  content  which  we  cannot  find  there. 
That  I  experience  a  certain  red  may  be  defined  as 
a  relation  between  red  and  the  other  factors  of  con- 
tent, and  we  do  actually  experience  relations  in  this 
connection;  but  the  relations  we  find  in  the  con- 
tent are  all  relations  which  determine  the  red  as  it 
is  experienced,  and  are  none  of  them,  severally  or 
together,  identifiable  as  the  experience.  On  the 
other  hand,  these  theories  simply  ignore  the  fact 


THE   EGO  339 

that  in  searching  the  content  for  any  sort  of  relations 
we  are  assuming  a  point  of  view  totally  outside  the 
content  from  which  to  make  the  inspection.  This 
omission  is  much  the  same  as  that  which  is  made  by 
those  philosophers  who  claim  that  the  universe  is 
just  one  substance,  which,  looked  at  in  one  way  is 
called  matter,  and  looked  at  in  another  way  is 
called  mind.  They  fail  to  see  that  the  point  of  view 
from  which  the  one  substance  is  looked  at,  now  this 
way  and  now  that,  is  something  assumed  in  addi- 
tion to  the  one  substance;  if  substance  is  strictly 
one,  and  if  there  is  nothing  else,  it  can  look  at  itself 
from  only  its  own  single  point  of  view.  When  we 
try  to  make  consciousness  depend  on  content  alone 
we  are  neglecting  the  fact  that  we  are  now  repre- 
senting consciousness  from  an  outside  point  of  view 
and  have  not  given  a  fair  account  of  conscious- 
ness till  we  indicate  how  we  got  to  this  point.  If 
we  represent  this  consciousness  in  any  sort  of  sym- 
bolic way,  as  we  may  represent  content,  it  is  ipso 
facto  not  adequate,  because  we  still  are  assuming 
a  consciousness  of  the  symbolization  without  which 
it  is  impossible. 

We  are  obliged  to  assume,  then,  a  point  of  view 
or  point  of  reference  over  against  content;  perhaps 
the    "transcendental    unity    of    apperception"    of 


340  A   SYSTEM   OF   PSYCHOLOGY 

Kant;  and  it  is  just  the  orientation  to  this  point  of 
view  which  constitutes  consciousness.  It,  of  course, 
cannot  be  symbolized  or  described,  because  as  soon 
as  it  is  described  it  becomes  no  longer  the  point  of 
view  to  which  the  consciousness  refers. 

We  speak  of  this  transcendental  point  of  view  as 
"  I."  The  "  I,"  if  we  accept  the  fact  of  it,  must  not 
be  supposed  to  be  active.  Activity  of  any  sort  is 
an  objective  fact  and  is  in  the  objective  world. 
The  "I"  is  the  pure  subject  and  is  incapable  of 
anything  except  being  a  subject. 

It  may  be  asked,  of  what  use  is  it  to  suppose  the 
"  I,"  which  has  no  qualities,  cannot  be  analyzed  or 
scrutinized,  and  can  do  nothing;  and,  also,  if  it  is 
not  describable  or  scrutinizable,  how  can  we  know 
it  is  there.  The  answer  to  both  questions  is,  that 
the  "I"  is  of  no  use,  but  that  our  analysis  of  the 
content  of  consciousness  presupposes  it,  and  hence 
we  admit  it.  We  do  not  observe  the  Ego,  but  it 
is  involved  essentially  in  every  observation.  It  is 
really  the  only  thing  that  observes  or  is  conscious: 
hence,  it  has  immediate  claim  to  existence. 

The  view  outlined  above  is  believed  to  be  that 
from  which  a  satisfactory  and  adequate  account 
of  consciousness  can  be  given.  It  is  a  view  which 
is  much   older   than   modern   civilization,    but   fits 


THE    EGO  341 

in  as  acceptably  with  scientific  psychology  as  with 
ancient  philosophy  and  religion.  It  is  the  only  view 
which  completely  justifies  the  universal  practice  of 
modern  psychology  in  leaving  the  "  I,"  or  Ego,  out 
of  its  analysis;  for  if  the  Ego  were  not  transcen- 
dental it  would  have  to  be  treated  analytically  in 
psychology,  instead  of  being  merely  assumed.  Be- 
ing transcendental,  the  Ego  has  practically  no  in- 
terest for  psychology  or  science. 

Modern  psychology  is  truly  said  to  be  psychology 
without  a  soul,  but  if  the  transcendental  point  of 
reference  or  subject  is  what  is  meant  by  the  term 
soul,  psychology  not  only  does  not  deny  the  soul, 
but  positively  affirms  it.  We  must,  however,  bear 
in  mind  the  fact  not  only  that  we  can  know  nothing 
about  the  Ego,  but  that  there  is  nothing  to  be  known 
about  it. 


CHAPTER  XXI 

THE   OCCULT 
I.  The  Study  of  the  Occult 

In  discussing  the  transcendental  Ego  we  were 
upon  dangerous  ground.  So  much  bias  exists 
among  those  persons  whose  fields  run  into  that  of 
psychology  that  it  is  impossible  to  make  any  state- 
ment, however  judicious,  concerning  the  Ego  with- 
out incurring  the  antagonism  or  contempt  of  some 
of  these  individuals.  The  same  conditions  sur- 
round us  in  the  discussion  of  the  occult.  It  is  quite 
noticeable  that  writers  who  have  expressed  opinions 
on  this  subject  have  met  with  a  great  deal  more  than 
intellectual  dissent  from  their  opinions.  Especially 
unpleasant  has  been  the  position  of  those  who 
have  agreed  with  none  of  the  extreme  views  on 
psychic  research,  and  in  consequence  have  been 
denounced  from  all  sides.  This  explanation  is 
necessary  in  order  that  the  student  may  know  that 
what  is  set  down  in  this  chapter  is  not  apt  to  be 

approved  by  even  a  considerable  minority  of  rep- 

342 


THE    OCCULT  343 

utable  scientists,  to  say  nothing  of  the  vast  com- 
pany of  fanatics. 

Just  what  is  here  meant  by  the  occult,  the  reader 
will  gather  as  he  proceeds.  The  things  treated 
under  this  heading  are  properly  the  subject-matter 
of  what  is  called  psychic  research,  but  in  one  way 
or  another  are  also  interesting  and  important  for 
psychology.  Psychic  research  is  at  present  in  dis- 
repute among  scholars,  largely  because  psychic  re- 
searchers do  not  take  a  logical  psychological  attitude 
toward  the  phenomena  they  investigate.  Psychic 
research,  the  investigation  of  phenomena  which  are 
alleged  to  be  not  in  accordance  with  accepted  views 
of  natural  law,  is  a  perfectly  legitimate  activity.  Its 
purpose  is  two-fold:  first,  to  accumulate  data  for 
psychological  study;  and  second,  to  rout  rascals  and 
to  dispel  popular  superstition. 

2.  Telepathy 

It  is  popularly  believed  that  the  thoughts  of  one 
person  may  directly  influence  those  of  another. 
This  belief  is  somewhat  akin  to  the  ancient  super- 
stition that  the  eye  of  one  person  is  able  to  affect 
another  person.  Vision  is  sometimes  called  touch 
at  a  distance,  and  it  is  hard  for  the  savage  (and 


344  A   SYSTEM   OF   PSYCHOLOGY 

philosophical  savages  are  still  extant)  to  believe 
that  when  his  eye  rests  upon  another  person  or  ob- 
ject something  does  not  go  out  from  his  visual 
organ  to  take  in  the  percept  of  the  other,  much  as 
his  finger  would  be  stretched  out  to  get  a  tactual  im- 
pression. From  this  naive  conception  of  the  phys- 
ics of  vision  the  belief  in  the  evil  eye  probably 
arises,  and  from  it  comes  also  the  harmless  super- 
stition of  the  present  day,  that  one  person  can  attract 
the  attention  of  another  by  gazing  intently  at  the 
back  of  his  head.  It  is  possible  that  the  fully  de- 
veloped eye-power  superstition  involves  the  alleged 
phenomena  or  thought-transference,  as  well  as 
the  supposed  power  of  the  eye  itself.  Telepathy, 
which  is  believed  in  by  many  persons  at  the  present 
time,  is  the  (alleged)  effect  produced  on  the  con- 
sciousness of  one  person  by  the  mental  operations 
of  another. 

As  a  matter  of  fact,  we  have  been  able  to  discover 
no  communication  between  persons  except  that 
which  takes  place  through  what  we  call  the  physical 
world.  I  may  have  the  sensation  which  you  have 
if  I  am  subjected  to  the  same  stimulus.  I  may 
think  of  the  object  of  which  you  are  thinking  if 
some  common  perception  is  associated  with  the 
object  in  each  of  us.      By  a  perfectly  definite  chain 


THE   OCCULT  345 

of  association  two  or  more  persons  often  arrive  with 
approximate  simultaneity  at  the  thought  of  some- 
thing which  has  not  been  directly  mentioned.  If, 
however,  one  person  thinks  of  a  certain  object 
because  another  thinks  thereof,  the  thought  of  the 
second  person  must  have  expressed  itself  in  some 
objective  sign  which  was  perceived  by  the  first  per- 
son, and  which  aroused  the  thought  of  the  given  ob- 
ject by  normal  association. 

Certain  interesting  phenomena  which  are  com- 
monly designated  by  the  term  "mind-reading" 
offer  confirmation  of  this  conclusion.  Mind-read- 
ing is  frequently  undertaken  as  a  parlor  amuse- 
ment, and  some  of  the  most  striking  results  are  ob- 
tained by  amateurs.  A  subject  may  be  sent  from 
the  room  while  the  remainder  of  the  company  de- 
cide on  some  act  he  is  to  perform  on  returning. 
The  subject  is  brought  in  by  two  of  the  company 
acting  as  guides,  usually  with  their  hands  on  the 
shoulders  of  the  subject.  All  the  company  think 
intensely  of  the  appointed  action,  and  the  subject  in 
many  cases  proceeds  to  perform  it,  after  more  or 
less  delay. 

Variations  may  be  introduced  into  such  an  ex- 
periment which  prove  that  the  subject  perceives 
(usually  marginally)  slight  pressure  sensations  from 


346  A   SYSTEM  OF   PSYCHOLOGY 

the  hands  of  the  guides,  which,  by  association,  bring 
up  the  idea  upon  which  the  designated  action  fol- 
lows. As  might  be  suspected,  the  experiment  suc- 
ceeds best  when  the  subject  is  convinced  that  he  is 
receiving  mental  influence,  and  fails  when  he  at- 
tempts to  interpret  pressure  sensations  consciously. 
Not  all  persons  succeed  as  subjects;  a  condition  of 
mental  equilibrium  is  required  in  which  slight 
associations  may  be  effective;  a  condition  not  easily 
obtained  by  every  one. 

Sometimes  the  mind-reading  succeeds  when  there 
is  no  contact  between  the  subject  and  any  one  else. 
Such  cases  are  very  few,  the  professional  demon- 
strations being  pure  humbug.  In  the  few  cases 
that  are  genuine,  the  subject  is  able  to  interpret 
changes  in  the  breathing  of  the  company  as  signs 
that  he  is  starting  to  do  the  right  or  wrong  thing,  or 
else  is  guided  by  faint  sounds  made  by  the  vocal 
organs  of  those  thinking  of  what  he  is  to  do.  The 
majority  of  adults  partially  articulate  words  in 
thinking,  and  this  slight  vocal  action  occasions  air- 
waves which  may  affect  the  ears  of  the  subject,  and 
thus  produce  the  effects  subconsciously.  If  the 
subject  be  blindfolded  and  have  the  ears  stopped 
(a  difficult  condition  to  obtain,  by  the  way),  mind- 
reading;  without  contact  will  in  no  case  succeed. 


THE    OCCULT  347 

There  is  a  wide-spread  belief  that  in  hypnosis  the 
patient  is  responsive  to  the  thoughts  of  the  hypno- 
tizer.  The  phenomena  of  hypnotism  are  some- 
times described  in  terms  of  the  influence  of  one 
mind  on  another,  but  this  influence  is  always  pro- 
duced in  the  normal  way — by  physical  signs.  The 
hypnotizer  may  think  as  much  and  as  intensely  as 
he  pleases,  and  the  patient  will  not  fathom  his  inten- 
tion unless  he  gains  some  inkling  of  the  thought  by 
visual,  auditory,  or  other  sensations.  In  certain 
cases  the  hypnotized  patient  may  interpret  signs 
more  readily  than  does  the  normal  subject,  but  such 
is  not  always  the  case.  The  exact  nature  of  the 
hypnotic  state  is  not  yet  clearly  understood.  The 
ideas  suggested  by  the  hypnotizer  occupy  the  pa- 
tient's mind,  driving  out  any  which  are  conceptually 
incompatible  with  them,  and,  if  they  are  ideas  of 
action,  the  actions  follow  mechanically  according  to 
what  we  would  expect  under  the  principle  of  ideo- 
motor  activity  when  all  checks  and  inhibitions  are 
removed.  This  description  of  the  hypnotic  state 
does  not  explain  it. 


348  A   SYSTEM   OF   PSYCHOLOGY 

3.  Mysticism 

Closely  related  to  the  theory  of  telepathy  is  the 
doctrine  of  mystic  knowledge.  This  doctrine,  which 
is  found  in  the  writings  of  many  modern  men  of 
letters,  comes  to  us  directly  from  the  Neoplatonic 
philosophy  of  the  so-called  Alexandrian  school. 
The  writings  formerly  ascribed  to  Dionysius  the 
Areopagite,  but  now  admitted  to  belong  to  the 
fifth  century,  embody  the  Neoplatonic  doctrine 
in  its  characteristic  form;  and  these  writings,  trans- 
lated and  studied  by  the  scholastic  philosophers, 
have  been  the  direct  sources  of  mediaeval  and  mod- 
ern mystical  beliefs. 

In  brief,  mystic  knowledge  is  supposed  to  be  a 
form  of  cognition  absolutely  different  in  character 
from  sense  perception  and  intellectual  apprehen- 
sion, and  vastly  superior  to  these.  In  ecstasy,  which 
is  the  technical  name  for  the  act  or  state  of  mystical 
knowledge,  the  subject  is  alleged  to  be  in  direct 
contact  with  some  form  of  ultimate  reality.  In 
Maeterlinck's  system,  this  ultimate  reality,  which  the 
soul  is  supposed  to  know  or  experience  in  this  mystic 
way,  may  be  another  soul:  in  the  original  system, 
and  the  system  of  certain  other  modern  mystics, 
(lie  reality  which  is  experienced  is  the  Divine  Being. 


THE    OCCULT  349 

The  nature  of  this  mystic  knowledge  is,  according 
to  the  theory,  indescribable,  because  it  is  entirely 
removed  from  the  sphere  of  ordinary  knowledge,  in 
which  sphere  only  are  descriptions  and  explanations 
possible.  The  statement  which  comes  nearest  to 
the  mystic's  doctrine,  is  that  in  ecstasy  the  soul  is 
united  with  God  (  or  with  another  soul). 

The  mystic  experience  must  be  carefully  dis- 
tinguished from  the  seeing  of  visions  or  the  hearing 
of  voices  (as  in  the  case  of  Joan  of  Arc),  and  from 
the  "  feeling  of  the  presence"  of  some  one — a  feeling 
in  which  many  people  believe.  The  mystic  experi- 
ence is  not  at  all  the  acquirement  of  the  ordinary 
form  of  knowledge  in  a  mysterious  way:  it  is  an  ex- 
traordinary form  of  knowledge.  The  experiences 
which  approach  this  condition,  but  which  remain 
in  the  ordinary  sphere,  may  be  conveniently  desig- 
nated as  pseudo-mystical. 

With  the  claims  of  mysticism  psychology  has 
strictly  nothing  to  do.  When  some  one  tells  me 
that  he  has  had  a  kind  of  experience  which  has 
absolutely  no  relation  to  my  experience,  I  have 
as  little  ground  for  admitting  the  (ruth  of  his  state- 
ment as  for  denying  it.  Nevertheless,  when  the  ex- 
perience of  another  person  can  be  satisfactorily 
explained  in  terms  of  our  own  experiences,  we  must 


350  A   SYSTEM   OF   PSYCHOLOGY 

provisionally  explain  it  in  that  way.  The  mystic 
distinctly  tells  us  that  in  ecstasy  there  is  conscious- 
ness— but  no  perception  or  imagination  or  intellec- 
tual process.  From  which  we  conclude  that  the 
experience — if  it  really  occurs — is  of  pure  feeling. 
This  conclusion  we  believe  to  be  satisfactory  and 
final. 

4.  Spiritualism  and  Mediumship 

A  large  and  varied  assortment  of  performances 
and  superstitions  have  come  to  be  included  under 
the  name  of  spiritualism  or  mediumship.  Me- 
diums, or  "psychics,"  or  clairvoyants,  pretend  to 
produce  table-tipping,  slate-writing,  playing  on 
musical  instruments,  and  other  physical  phenomena 
without  ordinary  physical  means.  They  read  the 
future  and  the  past,  and  put  you  in  communication 
with  Julius  Caesar,  or  Flashing-Eyes  the  Indian 
maiden,  or  your  great-grandfather.  A  few  words 
about  these  performances  are  appropriate  here. 

In  the  first  place,  supernatural  mediumships — 
the  production  of  physical  effects  without  adequate 
physical  causes — must  be  excluded  from  the  dis- 
cussion. The  table-tippings,  slate-writing,  "spirit- 
photographs,  "  and  other  tricks  have  been  explained 
and    exposed    until    they   have    become    merely   a 


THE    OCCULT  351 

source  of  weariness.  Every  supernatural  medium 
who  has  been  carefully  investigated  has  been  found 
to  be  a  fraud.  All  the  tricks  of  the  psychics  have 
been  done  by  Kellar  and  the  stage  magicians,  and 
many  of  the  performances  of  these  men  have  defied 
the  investigation  of  scientists,  until  the  magicians 
themselves  have  furnished  the  explanations. 

The  production  on  slates  or  other  surfaces  of 
writing  or  pictures  which  are  claimed  not  to  have 
been  produced  by  natural  hands  and  processes,  is 
conclusive  proof  of  fraud.  When  a  medium  causes 
a  table  to  tip  or  rise  into  the  air,  apparently  without 
physical  aid  or  support,  or  causes  voices  to  sound  or 
instruments  to  play,  which  voices  and  which  play- 
ing are  claimed  not  to  be  the  medium's  or  her  as- 
sistants', she  brands  herself  as  a  humbug.  The 
materialization  of  a  spirit  is  convincing  evidence 
that  the  medium  presumes  on  the  crassest  credulity 
on  the  part  of  her  patrons. 

In  other  cases,  the  mediums  are  possibly  honest. 
Psychic  healers  who  claim  to  heal  broken  bones  or 
bacterial  diseases  by  mental  treatment,  sometimes 
when  the  patient  does  not  know  that  he  is  being 
treated,  may  think  they  can  perform  these  miracles. 
People  have  always  believed  in  witchcraft  and 
sorcery,  and  the  sorcerers  themselves,  whether  voo- 


352  A   SYSTEM   OF   PSYCHOLOGY 

doo  doctors  or  "Christian  Science"  practitioners, 
are  usually  ignorant  enough  to  share  the  belief.  On 
the  other  hand,  the  psychic  treatment  of  nervous 
disorders  is  an  established  and  valuable  method, 
the  "mental"  state  of  the  patient  having  a  profound 
effect  on  his  "bodily"  functions.  Psychotherapy  is 
employed  by  scientific  physicians,  and  it  may  often 
be  employed  by  the  most  ignorant  sort  of  charlatans 
with  great  success.  If  the  patient  thinks  that  he  is 
receiving  treatment  and  is  being  benefited,  the 
benefit  frequently  follows. 

Psychic  treatment  cannot  take  the  place  of  other 
sorts  of  medical  treatment  where  these  are  indicated. 
In  diseases  of  other  than  nervous  origin  the  patient's 
state  of  mind  is  important,  but  its  importance  is 
relatively  small.  Many  patients,  of  course,  get  well 
without  medical  attention — physicians  do  not  claim 
to  "cure"  any  disease,  but  simply  to  assist  nature 
in  its  fight  against  it — and  many  cases  occur  in 
which  the  patient  thinks  he  has  a  disease  from  which 
he  is  really  free,  and,  upon  feeling  better,  he  may  be 
of  the  opinion  that  he  has  been  cured  of  that  disease. 
Hundreds  of  eases  of  cures  by  "  Christian  Science," 
which  are  described  as  having  been  cured  after  the 
patients  had  been  given  up  by  the  doctors  to  die  of 
a  disease,  have  been  investigated,  and  in  not  one 


THE   OCCULT  353 

case  out  of  fifty  has  it  been  found  that  such  a  diag- 
nosis had  actually  been  made. 

In  natural  mediumships  there  is  no  pretence  of 
effects  produced  in  a  supernatural  way.  If  writing 
and  other  phenomena  are  produced,  they  are  the 
work  of  the  medium,  and  no  claim  is  made  to  the 
contrary.  The  only  question  at  issue  is  as  to  the  sig- 
nificance of  what  is  written  or  spoken  by  the  medium. 

The  natural  mediums  usually  claim  that  what 
they  have  to  communicate  comes  from  the  "spirits" 
— a  "spirit"  takes  control  of  the  hand  or  the  vocal 
organs  of  a  medium  and  expresses  itself  by  means 
of  them.  This  hypothesis  would  explain  some  of 
the  remarkable  things  which  have  been  "  communi- 
cated" by  certain  mediums,  if  it  were  not  for  the 
fact  that  we  don't  really  know  what  we  mean  by  the 
term  "spirit."  The  "spirits"  would  seem  to  be 
decaying  fragments  of  former  personalities,  since 
their  communications  are  usually  trivial,  and  mixed 
with  much  pure  rubbish.  For  the  present  it  is 
safest  not  to  adopt  any  hypothesis  whatsoever  for 
the  explanation  of  natural  mediumship,  but  to  hold 
the  few  remarkable  results  of  experiments  with 
mediums  as  interesting  data  requiring  much  to  be 
added  before  any  explanation  can  be  attempted. 
It  is  by  no  means  impossible  that  it  may  all  be  ex- 


354  A   SYSTEM   OF   PSYCHOLOGY 

plicable  as  chance  and  cheating.  The  societies 
for  psychic  research  have  for  a  long  time  been  en- 
gaged in  investigating  all  cases  of  mediumship  which 
seem  geniune,  but  have  received  little  recompense 
for  their  labors.  Certainly  they  have  learned  noth- 
ing about  the  future  life — the  existence  of  persons 
after  what  we  call  death. 

It  is  to  be  noted  that  the  natural  mediums  who 
have  seemed  genuine  can  be  counted  on  the  fingers. 
By  genuine  is  here  meant  that  they  are  not  con- 
sciously trying  to  deceive :  that  the  information  they 
furnish  comes  from  a  source  unknown  to  themselves. 
The  large  body  of  professional  clairvoyants,  sooth- 
sayers, and  psychics  is  simply  a  group  of  impostors. 


REFERENCES 

The  student  is  urged  to  compare  the  view-points  and 
interpretations  of  the  foregoing  treatise  with  those  of 
other  texts.  The  most  important  shorter  treatises  are: 
Ward,  article,  "Psychology,"  in  the  Encyclopaedia  Bri- 
tannica,  eleventh  edition ;  Angell,  Psychology;  Titchener, 
Text-Book  of  Psychology;  Kiilpe,  Outlines  of  Psychol- 
ogy, and  Maher,  Psychology.  The  important  longer 
ones  are:  Ladd  and  Woodworth,  Elements  of  Physio- 
logical Psychology;  Wundt,  Grundziige  der  physio- 
logvschen  Psychologic;  Ebbinghaus,  Grundziige  der  Psy- 
chologic, and  James,  Principles  of  Psychology.  The 
last  named  is  the  most  important  of  all  in  point  of  theory. 

As  a  manual  for  the  further  study  of  the  data  of  psy- 
chology Ladd  and  Woodworth's  book  is  especially  to 
be  recommended.  Recent  books  and  articles  on  any 
topic  may  be  located  by  consulting  the  Psychological 
Index,  which  is  issued  annually  by  the  Psychological 
Review,  and  contains  all  the  titles  for  the  year  on  psy- 
chology, philosophy,  and  the  relevant  parts  of  neurology 
and  physiology. 

Below  are  given  a  few  references  on  points  which  are 
emphasized  in  the  foregoing  treatise,  some  of  the  articles 
being  in  agreement  with  our  positions  and  some  not. 

On  the  Greek  theory  of  the  psyche:  Turner,  "Aris- 
totle as  a  Psychologist,"  Catholic  University  Bulletin, 
XVII,  299-317;  Aristotle,  De  Anima  (in  Hammond's 
Aristotle's  Psychology),  especially  books  I  and  II. 

355 


356  REFERENCES 

On  the  original  use  of  the  term  psychology:  Hamil- 
ton, Lectures  on  Metaphysics,  Lecture  VIII.  The  defi- 
nitions of  the  present  science  of  psychology  given  in  stan- 
dard treatises  do  not  differ  much  from  the  definition  we 
have  given  in  chap.  I,  §  1.  Stout,  Manual  of  Psychol- 
ogy, Introduction,  chap.  I,  §  1,  gives  a  definition  which 
is  somewhat  broader  and  possibly  more  accurate.  The 
definition  given  by  Pillsbury,  Essentials  of  Psychology, 
does  differ  essentially  from  the  orthodox  one,  and  might 
be  made  the  basis  of  a  distinct  sort  of  psychology.  Pills- 
bury,  however,  virtually  abandons  his  definition,  and 
follows  rather  conventional  lines.  Kirkpatrick,  Genetic 
Psychology,  approximates  more  nearly  to  a  "behavior" 
psychology. 

On  the  restricted  meaning  of  consciousness:  Ham- 
ilton, "Philosophy  of  Perception,"  in  Discourses  on  Phi- 
losophy and  Literature.  See  also  Mill,  Examination  of 
Hamilton's  Philosophy,  chap.  VIII.  For  a  modern  dis- 
cussion of  consciousness,  see  Hicks,  "The  Relation  of 
Subject  and  Object,"  Proceedings  Aristotelian  Society, 
VIII  (1908),  161-214.  For  a  purely  functional  theory  of 
consciousness,  see  James,  "Does  Consciousness  Exist?" 
Journal  of  Philosophy,  etc.,  I,  477-491.  The  title  of 
this  article  is,  of  course,  not  to  be  taken  literally,  but  is 
to  be  understood  as  questioning  the  validity  of  a  certain 
theory  concerning  consciousness. 

On  elements  of  content:  Watt,  "The  Elements  of 
Experience,"  British  Journal  of  Psychology,  IV,  127- 
204. 

On  the  identification  of  sensation  and  brain  proc- 
ess: Loeb,  Comparative  Physiology  of  the  Brain,  chaps. 
I,  XV-XVIII,  and  especially  IX;   Forel,  Nervous  and 


REFERENCES  357 

Modal  Hygiene,  chap.  II;  Pearson,  The  Grammar  of 
Science,  chap.  II,  §  4.  Many  physiologists  who  prac- 
tically adopt  this  view  do  not  formulate  it  definitely. 
Certain  physiologists  explicitly  reject  the  theory:  see 
Howell,  Physiology,  pp.  182,  183.  Certain  others  grope 
in  utter  confusion,  making  absolutely  no  distinction  be- 
tween consciousness  and  object,  or  between  matter  and 
either  of  these;  see  McNamara,  The  Evolution  and 
Function  of  Living  Purposive  Matter,  in  which  the 
paragraph  in  the  middle  of  page  148  is  typical  of  the 
whole  book. 

For  a  clear  statement  of  the  parallel  theory  and 
the  arguments  for  it,  see  Mercer,  Sanity  and  Insanity, 
chap.  III.  An  instance  of  the  difficulty  found  by  even 
the  best  intentioned  parallelists  in  actually  maintaining 
a  position  on  the  theory  may  be  observed  by  attempt- 
ing to  interpret  the  section  headed,  The  Appearance  of 
Consciousness,  in  chap.  Ill  of  AngelPs  Psychology,  in 
the  light  of  the  statements  made  in  the  section  headed 
Terminology,  in  the  same  chapter. 

For  a  statement  of  the  interaction  theory,  see  Ladd 
and  Woodworth,  Elements,  pt.  III.  James's  Principles 
is  based  on  the  interaction  theory. 

For  Huxley's  theory  of  the  nature  of  matter,  see 
his  essay  on  "The  Physical  Basis  of  Life,"  particularly 
the  latter  portion  thereof.  On  this  problem,  see  also 
Mill,  Examination  of  Hamilton's  Philosophy,  chap.  XI. 

For  the  telephone  theory  of  audition,  see  Ruther- 
ford, "The  Sense  of  Hearing,"  Lancet,  1887,  I,  2-6. 
On  the  extensity  theory:  Ter  Kuile,  Pflilger's  Archiv, 
LXXIX,  146-157,  484-509;  Dunlap,  "Extensity  and 
Pitch,"  Psijchological  Review,  XII,  287-292. 


o58  REFERENCES 

On  musical  scales:  Ellis's  translation  of  Helmholtz's 
Sensations  of  Tone;  Sabine,  "Melody  and  the  Origin  of 
the  Musical  Scale,"  Science,  N.  S.  XXVII,  841-847. 
Naumann,  History  of  Music  (Praeger's  translation). 

On  visual  sensation  in  general,  the  articles  by  Nagel 
and  by  Von  Kries  in  Nagel,  Handbuch  der  Pkysiologie, 
are  especially  to  be  recommended.  See  also  Green- 
wood, "Studies  in  Special  Sense  Physiology,"  in  Hill, 
Further  Advances  in  Physiology  (1909).  On  the 
streaming  phenomena,  see  Wohlgemuth,  "On  the 
After-Effect  of  Seen  Movement,"  British  Journal  of 
Psychology,  Monograph  Supplement  No.  1. 

On  the  variability  of  the  temperature  spots:  Craw- 
ford, "A  Study  of  the  Temperature  Sense,"  Psyclio- 
logical  Review,  V,  63-112;  Kelchner  and  Rosenblum, 
Zeitschrift  fur  Psychologic,  XXI,  174-182. 

On  the  dissociation  of  dermal  sensation  qualities 
by  syringomyelia  and  other  nervous  diseases:  Starr, 
Organic  and  Functional  Nervous  Diseases. 

On   RELATIONS    AS   ELEMENTS  OF  CONTENT:   Huxley, 

Essay  on  Hume,  chap.  II ;  Woodworth,  "The  Conscious- 
ness of  Relation,"  Essays  Philosophical  and  Psychological 
in  Honor  of  William  James,  485-507 ;  McGilvary,  "The 
'Fringe'  of  William  James's  Psychology,"  Philosophical 
Review,  XX,  137-164.  An  interesting  attempt  at  the 
analysis  of  relations  is  contained  in  Spencer,  Principles 
of  Psychology,  second  edition,  II,  chaps.  XV-XXVI. 
See  also  Brunschwig,  Das  V ergleichen  und  die  Relation- 
erkenntniss.  The  specific  question  as  to  the  existence  of 
relation  content  is  involved  in  the  less  sharply  defined 
question  whether  or  not  "  imageless  thought"  exists,  and 
the  two  are  sometimes  confused.    On  imageless  thought, 


REFERENCES  •  »•">■' 

see  Titchener,  Lectures  on  the  Exjterirriental  Psyclwhgy 
of  the  Thought  Processes. 

On  images  and  ideas:  Aristotle,  De  Anima, book  III, 
chaps.  Ill  and  VII,  On  Memory  and  Recollection,  and 
On  Dreams  (in  Hammond,  Aristotle's  Psychology); 
Hamilton,  Philosophy  of  Perception,  foot-note  on  the  his- 
tory of  the  term  idea;  Alexander,  "On  Sensations  and 
Images,"  Proceedings  Aristotelian  Society,  X  (1909),  1-35; 
Colvin,  "The  Nature  of  the  Mental  Image,"  Psycho- 
logical Review,  XV,  158-169;  Angell,  "Methods  for  the 
Determination  of  Mental  Imagery,"  Psychological  Re- 
view, Monograph  Supplements,  XIII  (1),  60-108;  Stout, 
Manual  of  Psychology,  book  IV,  chap.  I. 

On  concept  and  judgment:  Mill,  Examination  of 
Hamilton's  Philosophy,  chaps.  XVII  and  XVIII. 

On  the  Platonic  "idea":  Plato  (Jowett's  transla- 
tion), Parmenides,  132,  Phcedo,  100-106,  Republic,  book 
VI,  and  especially  book  X,  596-598.  (The  numbers 
are  those  in  the  margins.). 

On  association:  Claparede,  L'association  des  idees, 
and  Calkins,  "Association,"  Psychological  Review, 
Monograph  Supplements,  I,  (2). 

On  space  perception:  Wundt,  Physiologische  Psy- 
chologic, sixth  edition,  II,  cap.  13,  §  5  and  cap.  14,  §  6; 
Ribot,  German  Psychology  of  To-day,  chap.  IV;  Sully, 
The  Human  Mind,  II,  Appendices  B  and  E;  Kolben- 
heyer,  Die  Sensorielle  Theorie  der  optische  Raumem- 
pfindung;  Von  Aster,  "Beitrage  zur  Psychologic  der 
llaumwahrnehmung,"  Zeitschrift  filr  Psychologic, 
XLIII,  161-203. 

On  time  perception:  Montague,  "A  Theory  of  Time 
Perception,"  American  J ournai 'of  Psychology ,  XV,  1-13; 


O 


60  REFERENCES 


Nichols,  "TheiPsychology  of  Time,"  same  Journal,  III, 
453-527.  Hamlin,  "  On  the  Least  Observable  Interval," 
etc.,  same  Journal,  IV,  564-575. 

On  the  question  whether  feeling  is  sensation  or  is  sui 
generis,  and  on  the  degrees  of  consciousness:  Titch- 
ener,  Lectures  on  the  Elementary  Psychology  of  Feeling 
and  Attention.  On  the  James-Lange  theory  of  the  emo- 
tions, see  James's  defence,  "The  Physical  Basis  of  the 
Emotions,"  Psychological  Review,  I,  517-529. 

On  rhythm:  Bolton,  "Rhythm,"  American  J ournal of 
Psijchology,  VI,  145-238;  Stetson,  "  A  Motor  Theory  of 
Rhythm,"  Psychological  Review,  XII,  250-270,  293-350; 
Dunlap,  "Rhythm  and  the  Specious  Present,"  Journal 
of  Philosophy,  etc.,  VIII,  348-354. 

On  the  subconscious:  Hart,  "The  Concept  of  the 
Subconscious,"  Journal  of  Abnormal  Psychology,  IV, 
351-371,  gives  an  excellent  outline  of  the  theory  we  re- 
ject; Jastrow,  The  Subconscious,  presents  implicitly  a 
theory  which  is  even  more  extreme. 

On  alterations  of  PERSONALITY  and  multiple  per- 
sonality: Prince,  The  Dissociation  of  a  Personality,  pre- 
sents an  extreme  view  strikingly,  and  illustrates  the  fact 
that  a  difficult  problem  may  be  literally  dramatized  to 
an  apparently  simple  solution.  Other  standard  books 
are:  Azam,  Hypnotisme  et  double  conscience,  and  Binet, 
The  Alterations  of  Personality.  See  also,  in  this  connec- 
tion, Janet,  The  Mental  State  of  Hystericals,  and  The 
Major  Symptoms  of  Hysteria. 

On  the  occult  in  general,  Lang,  Psychic  Research,  in 
the  Encyclopaedia  Britannica;  and  Moll,  Hypnotism 
(English  from  fourth  edition,  1910),  chap.  XIII.  On 
mind  reading  and  telepathy:  Moll,  op  cit.,  62,  63,  455- 


REFERENCES  361 

458, 510-519 ;  Pi*  ungst,  Clever  Hans  (Rahn's  translation) ; 
Hansen  and  Lehmann,  "Ueber  unwilkurliches  Fliistern," 
Philosophische  Studien,  XI,  471-530.  Curtis,  "Auto- 
matic Movements  of  the  Larynx,"  American  Journal  of 
Psychology,  XI,  237-239.  Laurent,  "  Les  precedes  des 
liseurs  de  pensees,"  Journal  de  Psychologic,  II,  481-495. 

On  mysticism:  Underhill,  Mysticism,  gives  the  best 
presentation  from  the  mystic's  point  of  view.  Jones, 
Studies  in  Mystical  Religion,  gives  an  historical  account. 
The  writings  of  (the  pseudo-)  Dionysius  the  Areopagite 
have  been  translated  by  Parker.  The  writings  of  Mae- 
terlinck and  of  Emerson  are  good  instances  of  the  mod- 
ern outcroppings  of  Neoplatonism  which  to  a  large 
extent  tincture  all  theological  discourse  of  the  present 
day.  See,  for  example,  Maeterlinck,  "The  Awakening 
of  the  Soul,"  and  "On  Women,"  in  The  Treasure  of  the 
Humble;  and  Emerson's  essay  on  The  Over  soul. 

Questions  concerning  dreams  must  have  been  sug- 
gested to  the  reader  by  several  portions  of  our  book, 
but  we  have  avoided  this  topic  because  so  little  is  known 
about  it.  Interesting  speculations  and  controversies 
concerning  dreams  are  rife  at  present,  but  the  state- 
ments of  these  would  be  too  long  for  this  treatise. 
The  student  may  profitably  read  two  books  which  rep- 
resent the  more  scholarly  attempt  to  study  dreams: 
Mourly  Void,  Ueber  den  Traum  (Klem,  editor),  and 
Foucault,  La  reve.  A  book  which  is  having  a  great 
vogue  at  the  present  time  among  medical  men,  and 
which  makes  of  an  arbitrary  theory  a  religious  dogma 
rather  than  a  scientific  hypothesis,  is  Freud,  Traumdeu- 
tung.  See  also  Jones,  "Freud's  Theory  of  Dreams," 
American  Journal  of  Psychology,  XXII,  283-308. 


INDEX 


Accent  in  rhythm,  311  ft". 

Achromopsia,  40,  67  ff. 

Action:  26.5  ff. ;  automatic,  274  ff.; 
and  the  subconscious,  326; 
habitual,  281  ff. ;  ideo-motor, 
267  If. ;  inst  inct i vi\  277  ff .,  282  f. ; 
reflex,  254  If.;  voluntary, 
269  ff. 

Adaptation,  protective,  51,  74, 
246. 

.Esthesiometry,  140  f.,  217. 

Affective  content,  243;  and  at- 
tention, 323  f. ;  in  mediate  as- 
sociation, 186;  and  the  self, 
287. 

Affective  elements,  14,  242;  in 
emotion,  15,  25.5  f. 

After-images;  distinguished  from 
secondary  sensations,  31  t.; 
negative,  76. 

Ageusia,  39,  48. 

Algo-hedonic  tone,  263  f. 

Alterations  of  personality,  291. 

Alternation  of  personalities,  331  ff. 

Amblacusia,  144  f. 

Anatomy,  8  ff. 

Anosmia,  39,  46. 

Apperception,  198. 

Appetition,  242  f. 

Apprehension,  16. 

Aristotle's  theory  of  imagination, 
16,  161,  153  ff. 

Art,  aim  of,  257  f. 

Association;  intellectual,  186  f.; 
mediate,  185  f.,  190;  physio- 
logical basis  of,  194  ff . ;  and 
perception,  209  ff. ;  principles 
of,  180  ff.;  and  recall,  178  f.; 
and  retention,  174;  strength 
of,  190  ff.;   and  vividness,  299. 

Associative  recall,  principle  of, 
187  ff. 

Attention,  293  ff.;  duration  of, 
313  ff.,  318,  323  f.;  and  inter- 
est, 301  f. ;   and  motor  adjust- 


ment, 294,  296;  scopeof,  304  f.; 

in  voluntary  recall,  193  f. 
Audition,  theoriesof,  81  ff.,  123  ff., 

143  f. 
Auditory  ossicles,  80. 
Auditory     sensations,      physical 

conditions  of,  80  ff.;    pitch  of, 

SI  ff. 

Beats,  30,  118  f. 

Betweenness,  216,  218,  232. 

Binocular  rivalry,  223,  225  f. 

Black,  67;  sensational  theory  of, 
60. 

Blind-spot,  55. 

Brain  centres;  auditory,  80;  as- 
sociational,  195;  of  cutaneous 
and  sub-cutaneous  sensation, 
85  f. ;  gustatory,  45;  of  imag- 
ination, 150;  olfactory,  50;  vis- 
ual, 54. 

Brain-paths,  194. 

Brain  processes,  actual  and  ma- 
terial, 21  f. 

Character,  personal,  289. 

Characters  of  sensation,  32  ff. 

Chiaro-oscuro,  223  f. 

Chromopsia,  40. 

Classification  of  sensation,  38  f. 

Clay's  theory  of  the  specious  pres- 
ent, 308. 

Clearness,  293. 

Cochlea,  80  ff.,  124. 

Co-consciousness,  332  ff. 

Cognition,  242. 

Color  adaptation,  74  ff. 

Color  blindness,  see  Achromop- 
sia. 

Color  circle,  64. 

Color  contrast,  76  f. 

Color  mixing  by  rotating  discs,  28. 

Color  onion,  65  f. 

Color  sensitivity  of  different  por- 
tions of  retina,  74. 


363 


364 


INDEX 


Color  theories,  59  ff.,  70  f.,  73,  79. 

Color  triangle,  64. 

Colors;  complementary,  66;  com- 
posite, 57;  elementary,  56  ff. ; 
fundamental,  57  f. 

Conation,  243;  and  imagination, 
250. 

Conative  feeling;  and  emotion, 
264;    spreading  of,  253  ff. 

Concept;  and  idea,  166  ff. ;  in  per- 
ceived content,  197  ff.;  devel- 
opment of,  198  ff.;  and  judg- 
ment, 303  ff. 

Confusion,  psycho-physiological, 
20. 

Consciousness,  6  f.,  292  ff. ;  de- 
grees of,  293  ff. ;  kindsof,  292  f., 
306;  span  of,  310;  time  rela- 
tions of,  306  ff. 

Conscious  processes,  180,  184  ff. 

Constant  errors,  108  ff. 

Content  of  consciousness,  7;  com- 
plexity of,  12;  elements  in,  13ff.; 
perceived,  196  ff. 

Convergence  and  accommodation, 
223,  225. 

Corresponding  points,  141  ff. 

Cortical  centres,  43. 

Dark  brown  taste,  49,  99. 

Deep  sensibility,  93  f. 

Deliberation,  271  f. 

Depth  perception,  visual,  222  ff. 

Descartes;  fundamental  formula, 
336;    theory  of  emotions,  259. 

Desire,  242  ff.,  250  ff . ;  in  volition, 
269  ff. 

Despair,  262. 

Determination,  274. 

Dichromopsia,  68. 

Dionysius  the  Areopagite,  influ- 
ence of,  248  ff. 

Direction,  spatial,  216,  222  f. 

Distance,  spatial,  217. 

Dizziness,  99. 

Duration,  232  ff. ;  and  algo-he- 
donic  tone,  246;  and  proten- 
sity.  35,  120  f. 

Ecstasy,  348. 

Edge-contrast,  77. 

Ego:  the  empirical,  285  ff.:  the 
real,  336  f. ;  functional,  theory 
of,  337  ff. ;  not  to  be  studied, 
337,  339,  341;   and  will,  271. 


Elements  of  content,  classifica- 
tion, of  13  ff. 

Emotions,  243,  255  ff.;  aesthetic 
and  religious,  257  ff. ;  classifi- 
cation of,  263;  and  eoenaesthe- 
sis,  259  ff. ;  cognitive  factors  in, 
261  ff. ;  and  feelings,  15;  mor- 
bid, 256  f . ;   and  volition,  270. 

Empiricism,  150. 

Epicritic  sensibility,  93  f. 

Error,  possibility  of,  24. 

Evil  eye,  the,  344. 

Experience,  6;  not  complex,  12  f.; 
and  brain  activity,  20  f. 

Extensity,  34,  83  f.;  auditory, 
215,  216;  differences  in,  122  t'.; 
and  extension,  122,  214  ff. ;  and 
intensity,  134  ff. ;  physiologi- 
cal basis,  123;  and  pitch,  123ff., 
215  f.;   and  space,  122. 

Extensity  theory  of  tone  percep- 
tion, 83,  123  ff. 

Extension,  214  ff. 

Fechner's  colors,  79. 

Fechner's  formula,  114  f. 

Fear,  260,  262. 

Feeling,  loose  use  of  term,  243. 

Feeling  tone,  35. 

Feelings,  243  ff.;  as  elements,  14  f,; 

and  vividness,  298. 
Fetichism,  252. 
Fiat,  271. 

Field  of  consciousness,  294. 
Focus  of  consciousness,  295. 
Fovea,  54. 
Franklin,  Mrs.;    Color  theory  of, 

62. 
Fringe     of    consciousness,     295, 

314  f. 
Fusions,  183. 

Galton's  questionary,  153  f. 

Gray  sensations,  65  ff. 

Groupings,  rhythmic,  309  ff. 

Gustation;  physical  and  physio- 
logical conditions  of,  44  ff. ; 
confused  with  olfaction,  45  ff. 

Gustatory  papilhe,  44,  4S. 

Habit,  281  ff. ;    and  alteration  of 

personality,  334. 
Hallucination,  203  IT. 
Hedonic  tone,  243;  and  conation, 

250,  255  f. 


INDEX 


:;<•,;> 


Helmholtz;  criterion  of  modality, 
42  f.;  theory  of  tone  percep- 
tion, 81,  84,  124,  143  f. 

Hering's  color  theory,  60. 

Huxley's  theory  of  matter,  26. 

Hypnotism,  268,  347. 

Idealism,  23,  24,  25,  150,  22S. 

Ideas,  163  ff.;  and  algo-hedonic 
feeling,  247  f.;  and  action, 
267  ff.;  and  conative  feeling, 
251;  and  volition,  270  ff.;  ab- 
stract, 166. 

Ideational  reflex,  267  ff. 

Illusion,  201  IT. 

Illusions  of  reversible  perspec- 
tive, 319  ff. 

Images,  14;  and  ideas,  163  ff., 
167;  as  copies  of  sensations,  16; 
spontaneity  of,  177  f. 

Imagination,  157  ff.;  306,  307; 
creative,  161  ff.;  function  of, 
160  ff.;  a  kind  of  consciousness, 
157;  perceptional  conditions 
of,  169  ff.;  physiological  proc- 
esses in,  155  f.;  reproductive, 
161;  in  science,  200;  and 
scientific  training,  165  f.;  types 
of,  154  ff. 

Imitation,  279  f. 

Instinct,  277  f. 

Integration,  principle  of,  180  ff. 

Intellect,  150  f. 

Intellectual  association,  principle 
of,  186  f. 

Intensity  of  sensation,  33,  109  ff. ; 
and  algo-hedonic  feeling,  245  f. ; 
and  \  ividness,  295  ff. 

Interactionism,  22,  25  ff. 

Interest,  242;  and  apathy,  251; 
and  attention,  301  f.;  spread- 
ing of,  252  f.;  and  subjective 
activity,  252. 

Intermittence  tones,  30. 

Intuition,  16. 

Irradiation,  135. 

.James- Lange  theory  of  the  emo- 
tions, 259  ff. 
Judgment,  303  f. 

Knowledge,  7;   mystical,  34S  ff. 

Learning;  accidental,  278  f.;  con- 
ceptual, 280  f.;  imitative,  279  f. 


Linnfeus'  classification  of  odors, 
52  f. 

Local  sign  of  sensation,  35, 137  ff.; 
and  complexity  of  odors,  145; 
differences  in,  139  ff.;  and  ex- 
tension, 139,  216,  222  f.;  and 
pitch,  143  ff.;  and  quality,  138. 

Love,  262  f. 

Margin  of  consciousness,  228,  295, 
314  f.;  two  sorts  of,  328  ff.;  and 
mind  reading,  345. 

Materialism,  25,  150,  228. 

Matter;  not  experienced,  19;  theo- 
ries of,  26. 

Mediumship,  350  ff.;  natural, 
353  f.;    supernatural,  350  ff. 

Memory,  174  ff.;  biological  and 
psychological,  174  f.;  and 
learning,  175  f.;  and  multiple 
personality,  331  f.;  and  recog- 
nition, 177;  and  plagiarism, 
176  f. 

Middle  term,  principle  of,  185  f. 

Mind:  a  multivocal  term,  5;  as 
brain  activity,  22;  as  objective 
reality,  23. 

Mind-reading,  345  ff. 

Modality  of  sensation,  42  f. 

Molecular  weight  and  olfactory 
sensation,  19,  53,  101. 

Mood,  emotional,  262. 

Motive,  272  f. 

Motor  tendency  of  thought,  284. 

Muscle  sensation,  96  f. 

Music  and  cognition,  258  f. 

Musical  ear,  144. 

Mystic  knowledge,  348  ff. 

Nausea,  97. 

Neo-Platonisni,       influence      of, 

348  ff. 
Nervous   process,    ambiguity    of 

term,  20. 
Neutral  point,  temperature,  88. 
Nystagmus,  99. 

Objects  of  consciousness,  7;  ma- 
terial, 19. 

Occult,  the,  342  ff.;  and  psy- 
chology, 3. 

Olfaction;  physical  conditions 
of,  19,  50  f.,  53,  101. 

Olfactory  region,  49  f. 


306 


INDEX 


Organic  sensations,  97  f. 

Osmic  sensibility,  variations  in, 

53  f. 
Overtones,  125  ft". 

Pain;  as  sensation,  86,  90  ft". ;  as 
feeling,  242  ft". 

Parachromopsia,  68  ft".;  detec- 
tion of,  69. 

Parallax,  223,  226. 

Parallelism,  25. 

Partials,  tonal,  125  ft.,  132  ft". 

Pathos,  260. 

Perception,  17;  and  the  concept, 
197  ft.;  of  things,  227  ft.;  true 
and  false,  201  ff. ;  causes  of 
false,  208  ff. 

Perceptual  reflex,  267. 

Personality,  alternating,  291 ; 
multiple,  331  ff. 

Perspective;  aerial,  223  f. ;  an- 
gular, 223,  225;  linear,  223, 
224  f. 

Photo-chromatic  interval,  65. 

Physics  and  psychology,  8  f.,  11. 

Physiological  reflex,  265  ff. 

Pitch  of  auditory  sensation,  81  ff., 
119,  123  ff.,  134  f.;  and  exten- 
sion, 124  f. ;  and  intensity,  135. 

Platonic  Idea;  and  the  concept, 
166;  and  Matter,  150;  and  re- 
lations, 149. 

Pleasantness,  242. 

Pleasure;  as  emotion,  262  f.;  as 
feeling,  242,  244  ff. 

Present  content,  17,  163. 

Present  moment;  actual  and  log- 
ical, 240  f.;  specious,  308  ff.; 
logical,  308. 

Process,  psychological,  184,  273  f. 

Protensities,  comparison  of,  121  f. 

Protensityof  sensation,  34, 120  ff.; 
arid  duration,  233. 

Protopathic  sensibility,  93  f. 

Pseudo-mystical  experience,  349. 

Psyche,  2. 

Psychic  and  psychical,  3. 

Psychic  research,  3,  342  ff. 

Psychological  analysis,  problems 
in,  185. 

Psychological  moment,  3. 

Psychology,  in  popular  usage,  3; 
definition  of,  4;  preparation  for 
study  of,  8;  and  the  soul,  2,  341. 

Psycho-physics,  114. 


Psychotherapy,  351  f. 

\ltv\o\oyia,  2. 

Qualities;  cutaneous  and  sub- 
cutaneous, 86  ff.;  gustatory, 
45;  kinsesthetic  and  ccenaes- 
thetic,  97  ff.;  olfactory,  52  f.; 
visual,  56  ff.;  schematization 
of,  62  ff. 

Quality  of  sensation,  33;  audi- 
tory, 83  ff. 

Rate,  temporal,  232,  236  ff. 

Recall,  177  ff.;  and  fading,  178; 
spontaneous,  177  f.;  volun- 
tary, 192  ff. 

Recognition,  175,  239. 

Redintegration,  principle  of, 
187  ff. 

Reflexes,  265  ff. 

Reinstatement,  principle  of, 
187  ff. 

Relations;  in  association,  186  f. ; 
directly  experienced,  14,  146  f, 
151;  elementary  and  complex, 
148  f.;  in  emotions,  262;  and 
fusions,  183  f. ;  imagined, 
165  ff.,  222;  and  logic,151  f.; 
motor  theory  of,  151;  neural 
conditions  of,  147  f. ;  and  Pla- 
tonic Ideas,  149  f.;  spatial, 
214  ff.,  222;  temporal,  230;  and 
vividness,  300  f.,  305;  in  vol- 
untary recall,  194. 

Relative  strength,  principle  of, 
190  ff. 

Relativity  of  sensation,  110  f., 
116  f. 

Repugnance,  242ff.,  250  ff.,  269  ff. 

Retention,  170  ff.;  conditions  of, 
172  ff.;  effective  without  re- 
call, 174;  individual  variations 
in,  171  f. ;  and  recall,  177;  and 
the  subconscious,  327,  329. 

Retinal  rivalry,  319. 

Retinal  streaming,  78  f. 

Rhyme  and  association,  189. 

Rhythm,  30S  ff. ;  and  association, 
189. 

Rods  and  cones,  54. 

Saturation,  chromatic,  63. 

Scale;  chromatic,  130  f.;  dia- 
tonic, 125  ff.,  128  ff.;  equally 
tempered,  131. 


INDEX 


:;<i< 


Scales,  primitive,  129,  130,  131. 

Secondary  phase  of  sensation, 
306  ff. 

Self,  the  empirical,  285  ff.:  di- 
vided, 289  ff.;  function  of, 
288  ff. 

Sensation,  14,  43  f.;  and  algo- 
hedonic  tone  244,  250;  charac- 
ters of.  32  ff . ;  and  image,  306  f., 
317;  lag  of,  27  ff.;  localiza- 
tion of,  137  ff.;  location  of,  23 
IT.;  and  nervous  process,  20  ff., 
25;  and  stimulus,  18  If.,  27  ff., 
109  IT.;    two  phases  of,  306  f. 

Sensation-continuum,  42  f. ;  vi- 
sual, 56,  57  ff. 

Sensational  reflex,  266  f. 

Sensations:  of  ache,  91,  100:  al- 
getic,  86,  90  f.:  auditory,  81  ff.; 
physical  conditions  of,  102  f.: 
classification  of,  38  f . :  camiES- 
thetic,  95,  97  ff.;  and  emotion, 
259  f.:  cutaneous  and  sub-cu- 
taneous, 86  ff. ;  dissociations  of, 

94  f. ;  end  organs  of,  84  f.,  94; 
topography  of,  92  f. :  of  effort, 
97:  Kiistatory,  44  ff.;  physical 
conditions  of,  103:  of  heat,  90, 
93:    of    itch.  91:    kinesthetic, 

95  ff.:  olfactory,  49  ff.;  physical 
conditions  of,  53,  101,  103.:  of 
pressure,  87  f.,  94:  secondary, 
31  f. :  subjective,  156:  tactual, 
86  f.,  92  f.:  terminology  of,  39, 
42:  titillatory,  87,  93  f.:  tricho- 
aisthetic,  39,  93:  visual,  56  IT.; 
physical  conditions  of,  101, 
103:   of  warm tli  and  cold,  88  ff. 

Sense  organs,  40  IT. 

Senses,  38  ff . 

Soul,  2,  341;  a  multi vocal  term, 
5. 

Sound  wave  a  continuous  stimu- 
lus. 31. 

Space;  and  auditory  perception, 
226  f.;  and  local  sign,  122.  139; 
mathematical,  212;  and  mus- 
cular sensation,  218;  three  di- 
mensional, 220,  223  ff.;  two 
dimensional,  217,  219. 

Space  perception,  theories  of, 
212  f. 

Space  relations,  213  f.,  222. 

Spaces,  co-ordination  of,  218  ff. 

Span  of  consciousness,  310. 


Spectrum,  chromatic,  56. 

Spinoza's  theory  of  emotion,  259. 

Spinozistic  monism,  339. 

Spirits,  353. 

Spiritualism,  350  ff. 

Stimulation,  intermittent,  28  ff. 

Subconscious,  the,  325  ff.;  and 
hypnotism,  328;  misuse  of  con- 
cept of,  173,  326  ff. 

Talbot-Plateau  law,  29. 

Taste  buds,  42  IT. 

Telepathy,  343. 

Telephone  theory  of  tone  percep- 
tion, the,  82. 

Temperature-zero,  89. 

Temporal  extent.  232  f.;  meas- 
urement of,  233  f.;  direct  es- 
timation of,  235  ff. 

Terminology,  principles  in,  5. 

Things,  metaphysical,  229;  per- 
ceived, 227  ff. 

Three  color  theory,  59  ff. 

Thresholds,  101  IT;  difference,  105, 
114  f.;  stimulus,  101  ff.;  two 
point,  139  ff.,  217. 

Timbre,  83  f.,  132  IT.;  schematic 
representation  of,  133. 

Time;  metaphysical,  231,  239; 
passing,  230  ff . ;  past  and  pres- 
ent, 238;  and  protensity,  121; 
and  retention,  172  ff. 

Time  order  and  recall,  189  f. 
Time     i>erception,     theories     of, 

229. 
Tone:  affective,  242  ff.;  and  neu- 
ral process,  245:   algo-hedonic, 
35,   243  ff.;    and    intensity  of 
sensation,  schematized,  245  f. ; 
and    sensation    duration,    246; 
and  imagination,   247  f.;    and 
repetition,  217;   conditions  of, 
248  ff.:  emotional,  243. 
Tone  intervals,  130. 
Traces,  mental,  170  f. 
Transcendental  unity  of  apper- 
ception, 339. 

Vedantist  theory  of  the  world,  23, 
24,  25. 

Vision,  single  and  double,  141  ff. 
Visual  acuity,  55. 
Vividness,  293  ff.;   and  efficiency 
of  thought,  302  f.;    factors  de- 


368  INDEX 

termining,  298  ff. ;  fluctuations  Wind  instruments  and   the  dia- 

in,  316,  318  ff.;  and  habituation,  tonic  scale,  127. 

314  f.;    and  intensity,  295  ff.;  Wish,  274. 
lower  limit  of,  325  f. 

Volition,    270    ff.;    as    activity,  Young-Helmholtz   color   theory, 

273  f.  the,  59  f.,  70  I.,  73,  79. 

Weber's  law,  1 1 1  ff .  Zwaardemaker's  classification  of 

White,  67.  odors,  52  f. 


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